Shouldn’t dbus-user-session package be listed as dependency as well?
The pipewire depends on pipewire-bin and pipewire-bin only recommends dbus-user-session.
Without dbus-user-session pipewire won’t work:
May 30 16:07:58 host systemd[827]: Started pipewire.service - PipeWire Multimedia Service.
May 30 16:07:58 host systemd[827]: Started wireplumber.service - Multimedia Service Session Manager.
May 30 16:07:58 host pipewire[2237]: spa.dbus: Failed to connect to session bus: Unable to autolaunch a dbus-daemon without a $DISPLAY for X11
May 30 16:07:58 host pipewire[2237]: mod.portal: Failed to connect to session bus: Input/output error
May 30 16:07:58 host wireplumber[2238]: Error acquiring bus address: Cannot autolaunch D-Bus without X11 $DISPLAY
May 30 16:07:58 host wireplumber[2238]: 0x56f0d7a40000: leaked proxy 0x56f0d7ae90d0 id:3
May 30 16:07:58 host wireplumber[2238]: disconnected from pipewire
May 30 16:07:58 host systemd[827]: wireplumber.service: Main process exited, code=exited, status=70/SOFTWARE
May 30 16:07:58 host systemd[827]: wireplumber.service: Failed with result 'exit-code'.
May 30 16:07:58 host systemd[827]: wireplumber.service: Scheduled restart job, restart counter is at 1.
May 30 16:07:58 host systemd[827]: Stopped wireplumber.service - Multimedia Service Session Manager.
May 30 16:07:58 host systemd[827]: Started wireplumber.service - Multimedia Service Session Manager.
May 30 16:07:58 host wireplumber[2248]: Error acquiring bus address: Cannot autolaunch D-Bus without X11 $DISPLAY
...
May 30 16:07:59 host systemd[827]: wireplumber.service: Start request repeated too quickly.
May 30 16:07:59 host systemd[827]: wireplumber.service: Failed with result 'exit-code'.
May 30 16:07:59 host systemd[827]: Failed to start wireplumber.service - Multimedia Service Session Manager.