After my many previous unsuccessful attempts at setting up a pci usb audio qube, decided to give it another try with a simple usb audio following that guide. Still no luck.
To debug this is another nightmare: the behavior is all over the place, and it doesn’t help that Qubes audio stack is ridiculous (pipewire over pulseaudio over alsa over that vchan module or whatever that crap is).
Debian works, BUT only when there is a bunch of other vms running? And only until the first reboot of client vms? (but this might be due to another random bug 
Sys-audio drops qubes on restart) If I start it first, then pavucontrol hangs on trying to connect to pulseaudio (the same happens on a fedora based vm, irrespective if I start it first or not). And OBVIOUSLY with a ridiculous audio stack I don’t even know if I should look for a pipewire service or a pulseaudio service or a pipewire-pulseaudio (that get removed in fedora if you follow the guide ) service…
So it very much would be appreciated if someone could finally provide a simple guide listing what packages need to be installed, what services need to be running, what permissions need to be granted, to get not pci audio, hell, not even usb audio, but a simple sys audio cube that would show client vm streams in pavucontrol reliably!
Update:
Okay, after more poking around it appears that both fedora and debian behave identically - setting sys-audio audiovm property to itself before it starts gets pavucontrol stuck trying to connect to puseaudio, but if it’s already started then client vms can connect to it until their first reboot. Also tried to install pipewire-qubes in both templates - no difference.