My question is similar to https://news.ycombinator.com/item?id=4682793 from five years ago: Which e-ink ebook reader can one buy if one wants to avoid things like remote wiping, creepy tracking of reading habits, and lock-in into a single store?
I'm currently using a Kobo Touch, which is fine except that its battery is starting to go. Also, I have to use a very old version of the firmware because at some point newer versions started to force you to connect to the Internet and register the device with Kobo just to be allowed to use the physical object you bought, and which until that point worked fine without registration.
I'm happy to sideload all my EPUBs via USB from my PC, so "never connect the reader to wifi" is OK for me. But I don't want to be forced to register an account with anyone at any point.
Good PDF display would be nice, but it's not particularly important for me.
It would be nice to have an open-source reader. We can buy all the bits: screen, single-board computer, batteries. All we need is some software.