I ended up solving a similar case for someone else, where ultimately different programs were fighting over control of the sound devices themselves. I have to s

I ended up solving a similar case for someone else, where ultimately different programs were fighting over control of the sound devices themselves. I have to say, that pipewire under NixOS had been easier to deal with than both pulseaudio and ALSA on crappy internal sound devices (i.e. ones requiring dmix and the like). It's nearly as plug&play as ALSA on "proper" soundcard was (like when I got a Dell Precision to work with that somehow had a Creative Audigy with 256 channel sound, so no need for dmix at all...)