Buddha didnt explicitly say you will become non returner there so I don’t know why you assume such a thing it may not even a pure abode/akannitha realm
There are many mind made realms
For example realm of streaming radiance
Dn1
As the cosmos contracts, sentient beings are mostly headed for the realm of streaming radiance. There they are mind-made, feeding on rapture, self-luminous, moving through the sky, steadily glorious, and they remain like that for a very long time
Even brahma realm is mind made too
Dn1
Then a certain sentient being—due to the running out of their life-span or merit—passes away from that host of radiant deities and is reborn in that empty mansion of Brahmā. There they are mind-made, feeding on rapture, self-luminous, moving through the sky, steadily glorious, and they remain like that for a very long time.
But if you assume that only in pure abode there is arahant that is wrong too
Since people can be an arahant just from this earth and all gods realms even in Neither perception nor non perception realm you can be an arahant there but only in pure abode the guarantee exists
Remember that mind made bodies are physical not mental
Dn9
What is a mind-made reincarnation? It is physical, mind-made, complete in all its various parts, not deficient in any faculty. What is a non-physical reincarnation? It is non-physical, made of perception
What are faculties here ?
Sn48.53
Furthermore, a mendicant who is an adept understands the six faculties: eye, ear, nose, tongue, body, and mind.
The buddha even scolded udayi for saying that mind made bodies are mental not physical
An5.166
Then the Buddha said to Venerable Udāyī, “But Udāyī, do you believe in a mind-made body?”
“For those gods, sir, who are formless, made of perception.”
“Udāyī, what has an incompetent fool like you got to say? How on earth could you imagine you’ve got something worth saying!”
What have physical and non physical to do with cessation attainment and non returner ?
The relationship is non-percipient being still have body
Furthermore There are many mind-made realms not just pure abodes so buddha may refer to non pure abodes mind-made realms here
Furthermore even if you are right you need to explain how cessation attainner that is even more subtle than formless attainner reborn in mind-made realms not formless realm
Furthermore what do gods in pure abodes do there ? If you think it’s serenity and insight practices then you are not right because only if you have developed both insight and serenity you can attain cessation attainment the buddha even said that you have developed ethics, immersion and wisdom
An5.166
Mendicants, take a mendicant who is accomplished in ethics, immersion, and wisdom
Now the non percipient being don’t do anything there I think they achieve temporary nibbana which is contactless,feelingless, consciousnessless,perceptionless, intentionless and sufferingless when their good merit is empty, feeling or equanimity feeling will arise in them so they fall from that plane
That’s why you should not delighting with nibbana or consider nibbana as self
What does accomplished in ethics, immersion and wisdom mean ?
An3.73
Then a noble disciple—accomplished in ethics, immersion, and wisdom—realizes the undefiled freedom of heart and freedom by wisdom in this very life
Mn12
Just as a mendicant accomplished in ethics, immersion, and wisdom would reach enlightenment in this very life, such is the consequence, I say
So you don’t need pure abodes at all you won’t even need to do anything at all if you are accomplished in those 3 And only in non percipient realm you don’t do anything at all Either physically or mentally
I hope I am clear enough and you see all of my 9 edits here, in the future I will propose that a thread can be locked while it’s being edited so you don’t reply to previous edit but the current edit, metta to you I hope you get to the supreme sanctuary