My chuthlu setup was not even connection at boot by the time I was done fiddling with the linked solution. I probably make mistakes.
Anyway I got two polycade devices and my only complaints are that there is a reset command that must be input and requires you to know which buttons are A B RT and RB, and to press those. Sadly windows controller setup tool doesn’t tell you which those are. I had a spare TR Fightstick which i used to plug the devices into, to trigger the reset. This should be two pins you can short, or a button on the pcb.
Also the devices do seem to enumerate consistently, which is they key, though mame thinks p1 is p2 and vice versa. but for $28 I can work with that…