{username, ...}: {
  # Public Keys that can be used to login to all my servers.
  users.users.${username}.openssh.authorizedKeys.keys = [
    "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIMzYT0Fpcp681eHY5FJV2G8Mve53iX3hMOLGbVvfL+TF ryan@romantic"
  ];
}