...and after trying another make and model of motherboard with Qubes 4.2, I still am having problems with hidraw devices (in my case, #Signet).

So next I'll try tails and see how that goes. If it goes like last time, it'll fail in exactly the same way as in Qubes.

At that point, I plan on doing another pair of backups, verifying them, and then reinstall with Qubes 4.1, which worked with my original motherboard.

The road is long, and costly.