Cyberdeck progress!

Amazingly, I am actually doing something right lol

So I have most stuff, except a power supply and a case. The case I already have a decent idea for, but I gotta get my hands on an actual power supply for it. But I was thinking... I'm using a Rii Mini i8 keyboard for it, and it has an internal battery. I wonder if I can use it to power the RPi as well, somehow.

Got no idea how I'll pull that off, though.