Set EDITOR env var in hm and fish shell

I’m trying to set the EDITOR env var home.sessionVariables.EDITOR = "nvim";.

However, this setting has no effect and the standard editor is still nano (default for nix). I’m using fish shell, btw. When I look at the fish config file, the env vars set by home manager should be getting sourced: fenv source $HOME/.nix-profile/etc/profile.d/ >/dev/null. And in that file, the EDITOR env var is actually set to nvim. Do I additionally need to install the foreign-env plugin for fish such that it works as expected?

You can add this to your system config

  environment.variables.EDITOR = "nvim";