I do this, but with keepass (keepass on all devices and then sync with nextcloud). Saved my butt a few times, I can go into the file history and pull an old version of the keepass db out of it, and then keepass has a merge feature, so I can pull the old file out, and merge with current to find missing records.
Anyway… backups good.
Older Boox’s weren’t certified for the Play store, so you couldn’t run play store apps, but that hasn’t been true for a while. You can run pretty much any Android app (though many don’t work well on e-ink), and the older Boox’s run older Android versions that aren’t compatible with many apps in the Play store even if they can connect.
I think you’re referring to “koreader” which started life as alternative kobo e-reader firmware, but now has an android port, but it just runs as an android app, that’s what I run on my Boox Palma, but if it reboots, I have to relaunch koreader.