I have finally gotten sound working. I needed to enable an alsa service (which also required the sound and possibly audio use-service-modules) aplay and speaker-test were failing, which seemed to possibly be due to a lack of /etc/asound.conf, and I found in the manual that the alsa service creates this file. After enabling that service, I just had to restart qutebrowser. As an aside, I think if our qutebrowser package were built with the optional pulseaudio support enabled, I would never have hit this issue. Although you could argue that having broken alsa was probably not good anyway.
I will finally close this issue.
