So following this gameboy build, only difference is I've moved my project to a Raspberry Pi 3 Model A+ to make this watch smaller. I didn't originally plan on downsizing to the Pi Zero, the smallest available, but after reviewing this guide, I need a board with a headphone jack, in order to hijack the soldering points of it for my speaker. 

Does any know of a way, I could have used a Raspberry Pi Zero, with a touchscreen and a speaker system??

But for this project, it will work just fine the path I'm following. Spent the day soldering all of those components together. 

As you can see from the second last photo, the power from the rechargeable LiPo battery connects to the system just fine. And the final photo, shows the connection of the speaker to the Raspberry Pi, hijiacking the headphone jacks soldering points. All of this is detail in the adafruit gameboy build instructions:

https://learn.adafruit.com/pigrrl-2/overview