Last update for today.
I got HRD Digital Master 780 working on the Pi 4B (haven't tested 3B+ yet).? It's not very fast on the Pi 4B 2GB, but it seems to work and accepts input sound from my Sabrent USB sound card.? This was apparently all I needed to install to get it to run:
winetricks allfonts
# If this doesn't ever start due to "This will hang until all wine processes in prefix=/home/pi/.wine terminate" then rebooting the Pi will fix that
# If this gets stuck forever in the middle of the installation, CTRL-C to cancel, then just run it again (it completed fine the second time I rand it)
# credits:?
I'll do a fresh Pi/ExaGear/wine install both Pi's and post some more refined install steps sometime.