While support is limited to a handful of models, due to a shortage of skilled maintainers, there are a few android tablets that support lineage OS, or postmarket OS.
Like OnePlus tablets, and Galaxy series tablets from samsung.
Good support from LineageOS for those. The Galaxy Tab A7, from 6 years ago, *IS STILL GETTING UPDATES* from Lineage, for instance.
LineageOS on android devices push their service lives *WAAAY* past what is normally doable. My now very ancient Pixel 4A is *STILL* getting monthly updates via LineageOS, for instance.
"nothing gets fixed"
Say again? What part of Monthly Updates did you not understand?
*IPv6 support*
My phone supports it natively. Dunno what you are going on about.
*superior AI*
This is a matter of personal preference, and I will assert that my preference trumps yours, when it comes to the device that *I* am using. Thank you very, very much.
*Able to play older games*
I can sideload on old android 2.x games on my phone fine-- Oh, wait, I said sideload, Thats a thing apple products cant do, isn't it? Awww.
*Unless they are old mac games, ironically*
Must really suck that Apple wont let you run interpreted code, huh? As for myself, I can run all kinds of stuff. Emulated game consoles, Winlator for older windows titles, BasiliskII for that classic mac experience you mentioned, ADosBox for classic DOS titles, all manner of stuff. Real shame apple doesn't let *ANY* of that play on their products!
*Able to use UNIX tools because its UNIX*
You do know that you can in fact get access to the console, without rooting, on android devices, right? There's any number of solutions for that, of varying quality, from the playstore-- and if you dont like any of those, you can sideload (Ohh--- there it is again!) F-DROID and get direct-compiled FOSS tools.
*Superior Hardware*
In what ways, exactly? They are all sealed units that you cant easily open, All have unremovable batteries, etc. If you mean "It has an alumalloy frame", I hate to burst your bubble, but there are plenty of such tablets in the android offering space. A great many android devices are built around very mature 3D rendering capable graphics chips as well, so when you load up things like Winlator, you can actually do D3D games on them. Not terribly well, since its ARM64 emulating an X86-64 CPU, but good enough for most things that you would actually find pleasurable to play on a tablet form factor.
*High performance graphically and otherwise for the cost*
Look above in the comments for how a savvy buyer saved over 1000$ buying an android tablet, then get back to me on that.