Ok, that is fair. Your suggestion to try to upgrade the OS to a higher version of Android is a good start, but, since the device is obscure (only word I could think of) that finding a custom ROM and Recovery would be daunting.Let's be fair: This is the OP's fun little project. As I understand it: He wants to push this tablet and see what it can do. If it can't be pushed far, so be it. Let's just see how far we can push it.
The idea of a clock isn't a bad idea if you are trying to go for the most pragmatic. Depending on how far OP wants to go with DIY, they could turn the tablet into a permanent calendar. It can sync to their calendar service of choice, and mount a frame to it to help hide the power connection. After that, mount it to the wall.
I am guessing on this one, but it could be an interface to a Ring doorbell? I don't know much about them, if it's even possible. I'd guess no as the Andoird API is too old?
If the OP has a small child, it could connect to a web camera and be the monitor for a baby?
That's about all I can think of for the moment