Hello,
Under Guix system, I also don't get sound through HDMI automaticaly. HDMI doesn't appear in pavucontrol's output but it does appear with gnome-settings and the likes so I suppose it's related to pulseaudio? My workaround in pavucontrol is to set Profile in the Configuration tab to something vaguely related to HDMI and it usually works. Maybe it could work for you too until we fix this properly? Hope it helps. Have a nice day, L p r n d n
