I created a new user on this system but anything with sound plain doesn’t work - the main user of the system has no issue though.
I already added the new user to the audio group, pulseaudio and pipewire are started by xfce during login too.
For example, when trying to open an mp3 file with mpv I get this:
[] The stream is suspended. Bailing out.
[] Failed to initialize audio driver 'pulse'
Could not open/initialize audio device -> no sound.
Audio: no audio

You don’t need
pulseaudioandpipewireat the same time becausepipewireprovides pulseaudio-compatible server (pipewire-pulse). Also,pipewireusually doesn’t requireaudiogroup. Did you follow the official docs or other online guide?