nixos-config/common/de/plasma6.nix

{
  services.desktopManager.plasma6.enable = true;

  services.xserver = {
    enable = false;
    libinput.enable = true;
  };

  services.displayManager = {
    sddm = {
      enable = true;
      wayland.enable = true;
    };

    defaultSession = "plasma";
  };
}