Auster

Any with good hardware as long as you can switch to stable and community-made ROMs.

If you like reading books, comics, etc, maybe Librera Reader?

Dunno how it is on Google Play, but it’s available FOSS and DRM free outside of it:
https://f-droid.org/packages/com.foobnix.pro.pdf.reader/

Same as the past 10 or so years, from what I can tell.

You also need to find instructions specific to your device on how to unlock the bootloader, and a TWRP specific to your device. From there, you do a clean flash through TWRP (erasing certain partitions and then installing the new ROM), and then, you should be good to go.

First, I’d suggest flashing a community system ROM. OEM systems are both very bloated, and stop being supported much earlier than community ones, so they’re not ideal unless you need to use it with some banking app or the sort. And if you don’t need Google’s services (de-Google, anyone?), I strongly recommend going for a vanilla system instead of a Gapps one.

Now, as stated in MargotRobbie’s comment, one good use is as a media player. If you can sideload stuff like VLC and Librera Reader, you should be covered.

You can also use it for some lighter gaming, if that’s your thing, as there’s plenty of emulators, wrappers and engine implementations for Android.

You can also use it for running servers, if you do this sort of stuff.

And if you like to test around with softwares, a spare Android device is pretty good to have.

Yes. ( also just remembered there are some mix up in naming conventions across the fediverse… "<.< )

Just checked your instance, and this page seems like a good start:
https://lemm.ee/communities?listingType=All&page=1

Then you can filter pages around, subscribe to pages as they pick your interest, etc.

Then, if it’s anything like Lemmy World about sorting (can’t verify since I don’t have an account in your instance), you can visit https://lemm.ee/?dataType=Post&listingType=Subscribed&page=1&sort=New to check all your subscribed contents, and by newest (I recommend “newest” because I get the impression posts start repeating themselves after a while with other sorting features).

If I may suggest, start following federated pages too. Each social media has its niche, and now, with federation that allows direct communications, it’s the perfect opportunity to find a social media whose features you like (which you seem to have already gotten), and curate your contents so it’s perfect for you without depending solely on your chosen social media’s niche.

Xiaomi mobiles aren’t available in the US

Maybe the OP could import one? Or are there sanctions even for importing?

If you absolutely must get something from Google Play, I suggest Aurora Store, which acts as an alternative frontend for Google Play, so you don’t have to have GApps installed.

If you have use for command line programs, Termux, a terminal emulator, is a great option, and it also works with root.

For reading eBooks, I also have a recommendation, Librera Reader (but I’ll check the OP’s recommendation too).

Material Files and Simple File Manager are great file browsing tools. But if you need a file browser for root specifically, I recommend Material Files specifically.

I use the Android app Librera Reader, since it’s the best one I could find that is officially distributed outside of the Play Store (de-google, anyone?).

You can find the APK on both F-Droid and GitHub.

For ebooks, since Librera doesn’t seem to be able to validate DRM (thankfully), I buy ebooks in DRM free formats, meaning I usually pend to Itchio, IndieGala, Fanatical, Humble Bundle, Story Bundle, etc.