I’ve been pretty happy with my kobo ereader. It can connect to the kobo store and work more or less like a kindle. You can also edit a config file on the reader and have it use a calibre-web instance as its primary store, which is what I do. That way you can seamlessly pull stuff from calibre and sync read status automatically. If you search for a book that’s not in calibre, your request gets passed through to the regular kobo store, no muss no fuss.

Older kobo stuff uses adobe digital editions DRM, which can be stripped with DeACSM but you’ll need an ADE account.

Newer stuff seems to be all epub.