Poetry2nix private registry, NETRC not set

I am trying to use poetry2nix with a private python package registry. After following these steps from the poetry2nix documentation, I still get an error “401 unauthorized” while calling nix develop . As I do not run NixOS, I added the NETRC envioronment variabel to the nix-daemon.service.

[Service]
ExecStart=@/nix/store/qmn396qsswazb8gqwjg1nj1jc226q8j4-nix-2.21.1/bin/nix-daemon nix-daemon --daemon
Environment="NETRC=/etc/nix/netrc"
KillMode=process

I reloaded the daemons and restarted nix-daemon but i still get error 401.

The env-vars file that is produced by adding --keep-failed to nix develop states:

...
declare -x NETRC=""
...

Any ideas?

so far I was able ensure that the netrc is mounted into the sandbox and that the user is a trusted user, so that my settings are not ignored.

Does any one know how to set environment variables in the sandbox?