Do not install pavucontrol on non-graphical installs.

nix/configuration/hosts/neelix/default.nix

@@ -29,4 +29,5 @@
   me.graphics_card_type = "intel";
   me.kodi.enable = true;
   me.lvfs.enable = true;
+  me.sound.enable = true;
 }

nix/configuration/hosts/odo/default.nix

@@ -49,5 +49,6 @@
   me.python.enable = true;
   me.qemu.enable = true;
   me.rust.enable = true;
+  me.sound.enable = true;
   me.sway.enable = true;
 }

nix/configuration/roles/sound/default.nix

@@ -8,10 +8,18 @@
 {
   imports = [ ];
 
-  environment.systemPackages = with pkgs; [
+  options.me = {
-    pavucontrol
+    sound.enable = lib.mkOption {
-  ];
+      type = lib.types.bool;
+      default = false;
+      example = true;
+      description = "Whether we want to install sound.";
+    };
+  };
 
+  config = lib.mkIf config.me.sound.enable (
+    lib.mkMerge [
+      {
         # rtkit is optional but recommended
         security.rtkit.enable = true;
         services.pipewire = {
@@ -72,5 +80,13 @@
             ];
           };
         };
+      }
+      (lib.mkIf config.me.graphical {
+        environment.systemPackages = with pkgs; [
+          pavucontrol
+        ];
 
+      })
+    ]
+  );
 }