After some help from @mc-hamster and digging through the files in VS Code, I noticed that there is the option of an external button for the middle button only already in the code.
Putting a button between GPIO 13 and GND mimics the middle button.
EDIT: Accidently found out that the pin labeled RST, is obviously for wiring a reset button as well.
For the power button, my original idea should still work, but isn’t really ideal.
I only want a middle button externally mounted, as I don’t want there to be a chance of being bumped and powered off. But I will continue to pursue the other two!