Swapping pulseaudio with pipewire-pulseaudio finally works with this update. However, it does not automatically enable the systemd unit files, which means one has to manually run

systemctl --user enable pipewire.socket
systemctl --user enable pipewire.service
systemctl --user start pipewire.socket
systemctl --user start pipewire.service

to get working audio. However, the systemd unit files can only enabled using the --user flag and not globally. This results in no sound on gdm.

Yeah it needs a systemctl --global enable pipewire-pulse.socket in the %postinstall for it to be a full drop-in replacement.

After replacing pulseaudio, the pipewire service and socket are not enabled. Hence by default this will break users' audio without manual intervention.