Here I (clumsily) demonstrate the process of porting a ps2avrgb based keyboard to QMK by using a multimeter to figure out the matrix, then put it into the code:
Keyboard is from here:
I did waste a bunch of time fixing the custom matrix scan logic, which it turns out was not necessary, as QMK has the logic already and it works on ps2avrgb. I got confused because the last ps2avrgb keyboard I ported DID need a custom matrix driver.
Maybe you’ll find it interesting or learn from my mistakes! I did get it working properly eventually