There are only two realities: saṅkhāra and asaṅkhāra; All others are paññatti

There are only two realities: saṅkhāra (dependent origination such as aggregate) and asaṅkhāra (no dependent origination such as nibbāna). All others are paññatti (concept;imagine;not reality) because saṅgkhāra must have tree sub-characteristics and asaṅkhāra must have not tree sub-characteristics. But paññatti has nothing, it can't arise like saṅkhāra and can't cease saṅkhāra like nibbāna.
By VN Parivāra of upāli-etadagga:

Aniccā sabbe saṅkhārā, dukkhānattā ca saṅkhatā; Nibbānañceva paññatti, anattā iti nicchayā.
Saṅkhāra, which means saṅkhata(effect-saṅkhāra)*, is anicca&dukkha&anattā; But only nibbāna&paññatti which are explained as only anattā.
(*Saṅkhāra, which means cause-saṅkhāra, use in more fixed meaning word, such as saṅkhāra-khandha, saṅkhāra-paṭiccasamuppāda. You can notice it in each context, because it is already appear clearly.)

And by KN Paṭisambhidāmagga of sāriputta-mahāsāvaka:

sabbe saṅkhārā aniccā sabbe saṅkhārā dukkhā sabbe dhammā anattāti
All saṅkhāra are anicca, all saṅkhāra are dukkha, and all dhammā are anattā.

There is no saṅkhāra which is not aggregates (Khandhavinimuttako hi saṅkhāro nāma natthi.)
Below, the second group is the conclusion of the first group, Sutta. Ma. Mū. Cūḷasaccakasuttaṃ:

"Aggivessana, 2 the Blessed One disciplines his disciples in this way; this part of the Blessed One's instruction is generally presented to his disciples: ('Form is inconstant. Feeling is inconstant. Perception is inconstant. Fabrications are inconstant. Consciousness is inconstant.) Form is not-self. Feeling is not-self. Perception is not-self. Fabrications are not-self. Consciousness is not-self. (All fabrications are inconstant.) All phenomena are not-self.' This, Aggivessana, is the way in which the Blessed One disciplines his disciples; this part of the Blessed One's instruction is generally presented to his disciples."

However, "All phenomena are not-self" in above context include more than "Form is inconstant", because it include more two, nibbāna and paññatti, as I have described above.
Abhidhamma and atthakathā have this same explanation as well.

Mind doesn't arise depend on only object

In abihdhamma (chapter 1-5 for mind&mind factor, chapter 6 for matter&nibbāna, chapter 8 for paṭiccasamuppāda&paññatti):
1 moment can separate to 3 sub-moments: arising, standing, and vanishing (upāda, ṭhiti, bhaṅgha).
1 matter moment = 17 mind/mind factor moments.
Paṭiccasamuppāda = cycle system of matter, mind, and mind factor.
Nibbāna = the opposite side of paṭiccasamuppāda.
Paññatti = imagination of mind&mind factors about paṭiccasamuppāda or nibbāna (everything).

• So, paññatti has no 3 sub-moments, we can't count it's moment.
• I.E. you can imagine "I get wings to fly", but it doesn't mean you really get wings. If the wings never get 3 sub-moments, arising/standing/vanishing, it is just imagination, not truth. However, something is imagination bases on truth, such as bird's wings. Because wings are imagination as well, but they base on the matter, which can get 3 sub-moments. So, bird can fly.

The explanation

1. Most of jhāna object is paññatti. No one can count paññatti-object's moment, because it never arise/standing/vanish.
2. Another, some jhāna has mind or perception as object. But that object is the past, which already vanished. Mind can know the present object as the present while it is taking a present moment (still in arising, standing, or vanishing state). but for the past or future object, mind can know it as it is unlimited. Similitude as we can see the present passing through car just the moment it is in our vision. But we can think of that passed/coming car, which being out of vision, unlimited.

By both case above, although the object is not present, the mind still can know it.
If mind have to arise depend on only object, we must know everything even when we are sleeping.

Whole pali canon focus on illusion analysis for purge illusion first

In tipitaka, only 121 minds, 52 mind-factors, 28 matters, and 1 nibbāna are not illusion. The other else are illusion. This is very important, because it is a start point to understand 3 characterizes.
12 paṭiccasamuppāda, both arising and cessation, are only the relativity of minds, mind-factors, matters, and nibbāna. They cause each other arise by themselves. If the practitioner still believe in an illusion, such as person, as the cause of 12 paṭiccasamuppāda, then he will not see the relativity of 12 paṭiccasamuppāda. Therefore, he can not meditate insight meditation in 3 characterizes in every second of life.

For the example, god is an illusion

1. When you still believe in god, do you understand 12 paṭiccasamuppāda of god?(no)
2. Then can you think God is impermanent, suffering, non-self? (no).
3. But if you understand how god can analysis as 12 paṭiccasamuppāda, then no god anymore right? (yes)
4. When no god anymore, 12 paṭiccasamuppāda, which you have been called it as god, can appear as impermanent, suffering, and non-self, right? (yes)

So whole pali canon focus on illusion analysis for purge illusion first

1. The first of all sutta, Sutta Pitaka Vol 1 : 1. Sutta. Tī. Sī Brahmajālasuttaṃ, is the biggest sutta which teaching about 62 self-illusion analysis. After buddha showed all 62 self-illusion, then buddha conclude them, 62 self-illusion analysis, as 12 paṭiccasamuppāda at the end.
2. The first fetter is sakkāya-diṭṭi, which have to destroyed by the practitioner first of all 10 fetters.
3. After jhāna meditation, whole tipitaka structure focus on diṭṭhi-analysis first for the insight meditation beginner, before comprehensions on "impermanent, suffering, and non-self".
4. Attavādupādāna-cessation, diṭṭhi-analysis/self purging, is taught only inside Buddhism according to MN Cūḷasīhanādasutta.
5. Sāriputta, the right-hand man of Buddha, described insight meditation by that same structure, in Sutta KN Paṭisambhidāmagga (whole structure).
6. 0 BE ancient commentary described insight meditation by that same structure.
7. 3th BE 3rd buddhist council members, arahanta, judge titthiya-monks by illusion analysis ability testing as well. See Abhidhamma Pitaka Vol 4 : Abhi. Kathāvatthu (whole structure).
8. 10th BE commentary, such as visuddhimagga (path of purification), described insight meditation by that same structure (whole structure).
9. 16th BE commentary, such as abhidhammatthasaṅgaha, described insight meditation by that same structure (whole structure).
10. Vimuttimagga described insight meditation by that same structure (whole structure).
11. Burmese monks, such as pa-auk monastery, described insight meditation by that same structure (whole structure).
12. Thai monks, such as Bh. Mun Bhuridatta who is the leader teacher of all thai forest monk, described insight meditation follow to abhidhammatthasangaha as well.

Self is paññatti. It is not grasping. Also, we choose to be mahāvihāra theravāda buddhist because we want to get all security.

Self is paññatti. It is not grasping. Grasping arise to attach/to cling khandha and paññatti, that are grasping's object. But paññatti never arise, so self never begin or end. Similarly, when you dream. The dreaming-mind is real and arising. But it's object never arise and never vanish, just an imagination of mind. So, self is not real.
Furthermore, for aggregates and grasping, in next life, is already taught that still arise until an ignorant and a craving still is not destroyed by arahanta's enlightenment . Because, there is a future-clinging-aggregate, and that clinging will try (kamma-bhava, kamma-becoming) to have (before death=get new thing, after death=rebirth) that future-clinging-aggregate. So in Khandhasutta taught:

"Whatever form — past, future (form-clinging-aggregate), or present; internal or external; blatant or subtle; common or sublime; far or near — is clingable, offers sustenance, and is accompanied with mental fermentation: That is called the form clinging-aggregate.

And Paṭiccasamuppāda taught:

From craving as a requisite condition comes clinging/sustenance. From clinging/sustenance as a requisite condition comes becoming. From becoming as a requisite condition comes birth.

Furthermore, we choose to be mahāvihāra theravāda buddhist (because we using mahāvihāra's tipitaka) because we want to have anytime and anywhere security by make every possible protection to protect every of your future self from every possible insecure. If you still lazy to protect your self from next life/rebirth (by making sure you [five aggregates] must never arise anymore), you are not mahāvihāra theravāda buddhist practitioner. Also, you never understand throughout the theravāda-tipitaka's concept.

Anicca, dukkha Vs Object of insight meditation Vs Anatta Vs Paññatti

Anicca, dukkha =whole 5 aggregates, both lokiya and lokuttara aggregates. Because they depend on many causes to arise.
Object of insight meditation=just 5 lokiya aggregate, except tanha. Because lokuttara aggregates can't not be attached by tanha, so practitioner must doesn't make vipassana on lokuttara. Another, tanha is samudayasacca, so practitioner must make tanha finish at all, not just make vipassana on tanha.
Anatta=everything and every objects=whole 5 aggregates, nibbana, and paññatti.
Paññatti=imagination (it is not reality, like a dream, never arise, no cause). Aatta (self) is one kind of paññatti, too.

See: abhidhammatthasangaha in 1st and 8th chapter.

the difference between aggregate existent, nibbāna existent, and nonexistent (paññatti)

the difference between aggregate existent, nibbāna existent, and nonexistent (paññatti):

Nibbāna has no cause, because nibbāna never arise (every aggregate arisen by causes). Nibbāna is reality, existent, because nibbāna is the end of suffering (5 aggregates), the opposite side of suffering.

But paññatti, such as space, is not reality, not existent, although we can know it. Because paññatti has not any cause, too. And mainly, it is neither included in aggregate existent, nor included in nibbāna existent. It is not arises by causes like aggregate, and not opposite side of suffering like nibbāna. Paññatti is imagination that is imagined by consciousness. So we can imagine paññatti follow to aggregate, nibbāna, paññatti, or not follow to anything (=wrong view). That magination of consciousness never arise, but aggregate can arise even though without imagine. We can not called "is made by" because paññatti never is made by causes. It is just imagination.

So, arahanta-phalasamāpatti is difference of paññatti, because arahanta-phalasamāpatti completely abadon evey akusala, before arahanta can realise nibbāna. But everyone can realise, imagine, paññatti.

This reply may look like general sutta that described about nibbāna, because this topic is the deepest topic in buddhism. So it is very hard to describe.

Difference Between Ultimate truths And Conventional truths

The separator, between them, are causes (to arising), and imagination.

Ultimate truths are not imagination, because they are effects that arise by their own causes. Except nibbana, ultimate truth, is the opposite of the other causes and effects, because nibbana is the cause of finshing of all causes and effects.

Conventional truths are imagination. They never arise and vanish. They just become to be the objects of consciousness, never arise.

Consciousness imagine conventional truth objects by some ultimate truths and some conventional truths, that it had known before. So the conventional truths never arise in real situation. But ultimate truths arise in real situation by their own causes, because they are effects, not just imagination.

The 1st-7th and first half of 8th chapters of abhidhammatthasangaha describe Ultimate truths.

The last half of 8th chapter of abhidhammatthasangaha describe Consciousness truths.

http://www.palikanon.com/english/sangaha/sangaha.htm