It's a shame that Kindles aren't hack-friendly, there are lots of old Kindles lying around that would be great as an always-on display.
[1] https://wiki.mobileread.com/wiki/Kindle4NTHacking#Jailbreak
So it would be the same basic principle here as what you envision.. boot into that other system, but have it instead launch some other app.
Too bad. There are probably other use cases for "keep the screen on continuously".
> It's kind of finicky as well: I would have the network selector pop-up and stay there if there was a temporary disconnection in the WiFi (say if someone used the microwave).
Now this I've never seen. The WiFi is pretty solid here, though... there are 5 WAPs in different parts of the house (primarily so I can get signal out to the edge of the yard -- the house is only medium-sized)..