I wanted a low-effort epaper weather station, so I got a "Barnes and Noble GlowLight 4e" e-reader. It runs Android, and can have normal apps installed pretty easy.
Info is from here. Steps:
FYI, since this is an epaper device, einkbro is a good browser choice. I installed via APKPure's app, since while they have the app as a plain file on their site, it's in a weird xapk format that adb can't eat, but their app can install it directly.
The default settings program doesn't let you turn off the screen timeout, but just set the delay between 2 min and 60 min. Further, for some reason, the developer panel option to disable screen timeout when charging doesn't work.
Using adb over USB, we can get the "real" android settings screen to come up: run "adb shell am start -a android.settings.SETTINGS". (Info from here.)
From there, you can find the screen timeout and set it to "Never".
I got an older original "Nook GlowLight Plus eReader" (model BNRV510), and it struggles with Firefox and most anything.
You can adb install stuff as documented above, but the lanucher and browser referenced are too much. Instead:
Launcher: ReLauncherX from here. Mirror of APK here.
Browser: "Blitz Browser" (hacked up Lightning browser). Specific APK here. Mirror.