nix-configs/modules/desktop/locale.nix

{ ... }:
{
  time.timeZone = "Europe/Berlin";
  i18n.extraLocaleSettings = {
    LC_LANG = "en_US.UTF-8";
    # LC_LANGUAGE = "en_DE:en_US:en_GB:de_DE";

    # ISO 8601 (hopefully)
    LC_TIME = "en_DK.UTF-8";

    # why is this even a thing
    LC_COLLATE = "C.UTF-8";

    LC_ADDRESS = "de_DE.UTF-8";
    LC_IDENTIFICATION = "de_DE.UTF-8";
    LC_MEASUREMENT = "de_DE.UTF-8";
    LC_MONETARY = "de_DE.UTF-8";
    LC_NAME = "de_DE.UTF-8";
    LC_NUMERIC = "C.UTF-8";
    LC_PAPER = "de_DE.UTF-8";
    LC_TELEPHONE = "de_DE.UTF-8";
  };
}