Thank you for the suggestions. I think I found a solution, at least theoretically. I'm posting for any future cheap bastards like me.
I found a 7" tablet with a damaged battery for as low as $4 on an ebay-like website in my area. The good thing is that it comes with the battery so I'll be able to salvage its circuit and make it run off of my main power source. Then I will use a VNC app to connect it to the PI. Since my PI is set up as an access point the tablet will connect to it (Super lucky! But it could also work if they're in the same network).
So far so good, I've ordered it and will post back if it doesn't work out.
Last edited by manix
on Thu Jul 25, 2019 3:22 pm, edited 1 time in total.