nixos/services/fprintd.nix

{
  config,
  lib,
  ...
}:
with lib;
  mkIf (elem "fprintd" config.machine.services) {
    security.pam.services = let
      unlock = [
        "sudo"
        "i3lock"
        "login"
        "lightdm"
      ];
    in
      listToAttrs (forEach unlock (n: {
        name = n;
        value = {fprintAuth = true;};
      }));

    services.fprintd = {
      enable = true;
    };
  }