I've installed nix in my user environment and an override to the nix-daemon systemd config.
/etc/systemd/system/nix-daemon.service.d/override.conf [Service] ExecStart= ExecStart=@/home/thk/.nix-profile/bin/nix-daemon nix-daemon --daemon This is not elegant at all, but works. Eventually I want to move to NixOS anyways, so elegance on a Debian system is not my first priority.