Thanks for the reply and suggestion abrugsch.

I just got a beaten up old gba sp yesterday so stripped that out for the motherboard after making sure the actual gameboy works.
Just need to figure out what i'm doing in regards to wiring as i've not done electronics for a fair few years.

This has inspired me to actually create one for myself. Collected all the bits apart from the screen currently as i'm still unsure whether a teensy or the controller on a gpio ports is the way to go if i get a spi tft rather than the adafruit as there is a £25 difference roughly. I will have to make...