Gday @Mr.Tuesday & welcome to the forums
this is definitely the place to come for all the goodies and hot tips for young players…
you are sure to find the answer you’re looking for and the right minds to help you along.
the MMJoy PCB i’ve designed would be an excellent starting point for you
(if it were available) MMJoy PCB design
unfortunately with the current situation, lockdowns etc. progress has dwindled away a bit, but we are about to revisit it again to get our first test batch produced.
hopefully following that we will have a working production model to begin fabricating.
In the meantime, the ProMicro (arduino clones) and shift register dev boards are readily available on aliexpress and similar sites.
you can also find some walkthroughs on the tech here:
http://avimator.net/229wiki/index.php/Shift_Register
http://avimator.net/229wiki/index.php/TLE5010
Please note electronics is NOT my field, I have picked the brains of as many people whom I could to understand the minimum to produce my own switch panels etc.
I have written these guides as best i could to provide the information that anyone could understand (even myself) 
As discussed the MMJOY PCB doesn’t do anything particularly special compared to them, we were just trying to produce something very user friendly, whilst applying ourselves to the learning curve of PCB design
cheers