There are certainly a lot of builds and DIY guides on how to turn your Raspberry Pi Zero (Or Zero 2) into a handheld emulator console running RetroPie. In fact, the first guide and the one I based my project on was made by Adafruit. It is a very good guide and really easy to follow!
But, personally, I had some issues with the design, mostly the amount of soldering required to make the Build and the number of PCBs necessary for it. Another deal-breaker I found was the lack of sound! Especially when I consider that some of the tunes on those old games are fantastic and nostalgic!
So I decided to make my own Build and address the following issues:
1.- All in one PCB solution for the Buttons, the LiPo Battery charger, and the step-up voltage converter.
2.- The PCB will also have an audio amplifier and a speaker to allow for audio reproduction.
3.- The Formfactor will be similar to the GBA SP gamepad.