I’ve been looking for an excuse to run MakeCode Arcade games on my a Raspberry Pi. 
I started with my Raspberry Pi Zero WH. I have this neat, wooden case from C4Labs. (It’s called the Zebra Zero Plus, if you’re interested.) I didn’t have any microswitch buttons handy, so I stopped by my local Radio Shack store and picked up a few. (Yes, we still have a Radio Shack in our area.) I followed the guide on the MakeCode Arcade documentation site, put the software on an SD card, et voilà! (In the photo, you can see the Raspberry Pi 3A+ anxiously awaiting to get in on the action.) I even loaded Crazy Tennis! onto the device via USB. Works like a champ!
After confirming that the buttons and wiring worked properly on a Raspberry Pi Zero, I connected the wires to the GPIO on my Raspberry 3A+. After swapping out the software (the 3A+ uses different software), I hooked up the 3A+ to my monitor, and it worked almost the same as the Zero. The kit that I bought at Radio Shack even had the elusive USB-A-to-USB-A cable, so I could load games on it via USB just like with the Zero!
The only thing that I couldn’t figure out was how to reset the device to get back to the menu and select a new game. I had to power down the 3A+. Once I reapplied power, I was taken back to the menu, complete with any games that I loaded via USB.
So, I can confirm that the guide and the software do indeed work with a Raspberry Pi 3A+. I now have an excuse to get a Pimoroni PiCade … or maybe I’ll just build a cabinet myself.
Great way to spend a rainy Saturday afternoon!