ok you are right that it works. i just don’t understand where the “user-environment” pipewire is comming from:
[olaf@nixos:~]$ systemctl --user status pipewire
● pipewire.service - PipeWire Multimedia Service
Loaded: loaded (/etc/systemd/user/pipewire.service; linked-runtime; vendor preset: enabled)
Drop-In: /nix/store/9x3yg7yb9cb9vd8ka7g51wbqf0gfd7h5-user-units/pipewire.service.d
└─overrides.conf
Active: active (running) since Wed 2022-03-30 17:19:41 CST; 1h 20min ago
TriggeredBy: ● pipewire.socket
Main PID: 1380 (pipewire)
Tasks: 2 (limit: 19085)
Memory: 4.7M
CPU: 1.414s
CGroup: /user.slice/user-1000.slice/user@1000.service/session.slice/pipewire.service
└─1380 /nix/store/y9f9bbwl3jyslhsyhp21v2507q5mrjg7-pipewire-0.3.49/bin/pipewire
Mar 30 17:19:41 nixos systemd[1280]: Started PipeWire Multimedia Service.
[olaf@nixos:~]$ whereis pipewire
pipewire: /etc/pipewire /nix/store/lirmg3cwnahcwsvvrb4gwakwkykn89rx-user-environment/bin/pipewire /nix/store/wnqiw6mp0sh8iba8288gfxzl94j547m3-system-path/bin/pipewire
[olaf@nixos:~]$ /nix/store/lirmg3cwnahcwsvvrb4gwakwkykn89rx-user-environment/bin/pipewire --version
/nix/store/lirmg3cwnahcwsvvrb4gwakwkykn89rx-user-environment/bin/pipewire
Compiled with libpipewire 0.3.48
Linked with libpipewire 0.3.48
[olaf@nixos:~]$ /nix/store/wnqiw6mp0sh8iba8288gfxzl94j547m3-system-path/bin/pipewire --version
/nix/store/wnqiw6mp0sh8iba8288gfxzl94j547m3-system-path/bin/pipewire
Compiled with libpipewire 0.3.49
Linked with libpipewire 0.3.49
its from some nix-env attempt a few days ago.