Do not install qemu on neelix.

nix/configuration/flake.lock

@@ -327,7 +327,7 @@
       },
       "locked": {
         "lastModified": 1,
-        "narHash": "sha256-5DWw7GnwVZ98HUp/UUJcyUmmy9Bh/mcQB8MQQ0t3ZRo=",
+        "narHash": "sha256-H2OXIXbpDg2ngo92lzPLYc61QM6M/d5UyHGUCSRztzA=",
         "path": "flakes/zsh-histdb",
         "type": "path"
       },

nix/configuration/hosts/odo/default.nix

@@ -48,4 +48,5 @@
   me.media.enable = true;
   me.python.enable = true;
   me.sway.enable = true;
+  me.qemu.enable = true;
 }

nix/configuration/roles/qemu/default.nix

@@ -8,7 +8,22 @@
 {
   imports = [ ];
 
-  environment.systemPackages = with pkgs; [
-    qemu
-  ];
+  options.me = {
+    qemu.enable = lib.mkOption {
+      type = lib.types.bool;
+      default = false;
+      example = true;
+      description = "Whether we want to install qemu.";
+    };
+  };
+
+  config = lib.mkIf config.me.qemu.enable (
+    lib.mkMerge [
+      {
+        environment.systemPackages = with pkgs; [
+          qemu
+        ];
+      }
+    ]
+  );
 }