Nice project! I have a couple of RetroPie machines. One in a PiCade and the other is attached to the TV in the lounge. Would be nice to have one in a totally portable form factor. I lust after the modded gameboy versions I see online all the time
Using this cable I’ve managed to cram a 5" screen, RPi Zero, WIFI dongle, audio filter, amp, speakers and some controls into a wedding album - so it would be possible to watch videos whilst looking through the photo’s too. Turned out not too bad
I also grabbed one of these from Amazon when they were reduced to a few pounds:
Eventually managed to get a screen, RPi-3 and all the extras inside the case. Put additional buttons to for start/select/coin insert etc too. Sadly, the joystick on these is pretty poor, but still sufficient enough for a little retro dabble now and then.