Hi @Scavy,
here is my return of experience as I have both a P3b gamehat and some home made gameboy zero:
- Gamehat :
- Very easy to put together. Just plug the P3b, the battery and you're good to go.
- P3b performance is better than pizero for emulation (especially snes, gba, ps1)
- The buttons are very "clicky" so it either you like it or hate it. One thing for sure is that it is impossible to play discreetly
- The form factor is good for big hand but rather cumbersome and the edges are sharp. It is possible to improve it with 3D printed cases. The same goes for the buttons that you can replace with rubber membranes based ones, but it requires soldering and 3D printing in the end.
- the battery last around 2 hours, a bit more maybe depanding on the quality and capacity. Note that it is recommended to use a P3b instead of a P3b+ as it consumes a bit less power.
- Gameboy zero (or GPI case):
- the GPI case seems also very easy to assemble, but the pi zero is more limited for emulation.
- Snes games overall does not play full speed and GBA is only playable using GPSP who is not compatible with some games (golden sun for example).
- Battery lifetime should be more with a pizero, but will require modification of the GPI case to use rechargeable batteries with higher capacity.
I hope it will be useful!