base: put common GUI programs behind option

base/default.nix

@@ -1,6 +1,7 @@
 { ... }:
 {
   imports = [
+    ./gui-programs.nix
     ./networking.nix
     ./nix.nix
     ./programs.nix

base/gui-programs.nix

@@ -1,31 +1,35 @@
-{ pkgs, ... }:
+{ pkgs, lib, config, ... }:
 {
-  environment.systemPackages = with pkgs; [
-    element-desktop
-    feh
-    firefox
-    ffmpeg
-    gimp
-    gnome.nautilus
-    imagemagick
-    mpv
-    obs-studio
-    pavucontrol
-    slack
-    spotify
-    tdesktop
-    teams
-    thunderbird
-    virt-manager
-    zathura
+  options.my.gui.enable = lib.mkEnableOption "System has some kind of screen attached";
 
-    unstable.discord
-  ];
+  config = lib.mkIf config.my.gui.enable {
+    environment.systemPackages = with pkgs; [
+      element-desktop
+      feh
+      firefox
+      ffmpeg
+      gimp
+      gnome.nautilus
+      imagemagick
+      mpv
+      obs-studio
+      pavucontrol
+      slack
+      spotify
+      tdesktop
+      teams
+      thunderbird
+      virt-manager
+      zathura
 
-  networking.networkmanager.enable = true;
-  programs.nm-applet.enable = true;
-  programs.steam.enable = true;
+      unstable.discord
+    ];
 
-  # NOTE: needed for home emacs configuration
-  nixpkgs.config.input-fonts.acceptLicense = true;
+    networking.networkmanager.enable = true;
+    programs.nm-applet.enable = true;
+    programs.steam.enable = true;
+
+    # NOTE: needed for home emacs configuration
+    nixpkgs.config.input-fonts.acceptLicense = true;
+  };
 }