That’s stupid. Nothing stops you from just installing regular Ubuntu if you love snaps so much.

There’s Librera FD, on F-droid. It’s the open source version of Librera on the google play store. I believe it strips out the google api/cloud stuff, but its db /reading status/etc are all easily synced via Nextcloud (which is what I do). The only real negative I’ve found with it is that it’s search for text in books is slow compared to more popular reading apps like Moon+ Reader.

This must be some weird American thing. I’ve gotten pixels on contract before in my country and I can OEM unlock and flash them no issue. If you don’t pay the cell carrier will just blacklist the IMEI. They don’t lock down the device itself.