Add Support for Unfree Packages with pkgs.unfree

flake.nix

@@ -14,11 +14,21 @@
       inputs.nixpkgs.follows = "nixpkgs";
     };
   };
-  outputs = { self, nixpkgs, sops-nix, nix-matlab }@attrs: {
+  outputs = { self, nixpkgs, sops-nix, nix-matlab }@attrs: let 
-    nixosConfigurations.kcnhub = nixpkgs.lib.nixosSystem {
     system = "x86_64-linux";
+    unfree-overlay = final: prev: {
+      unfree = import nixpkgs {
+        inherit system;
+        config.allowUnfree = true;
+      };
+    };
+    applyOverlays = overlays: ({...}:{ nixpkgs.overlays = overlays; });
+  in {
+    nixosConfigurations.kcnhub = nixpkgs.lib.nixosSystem {
+      inherit system;
       specialArgs = attrs;
       modules = [ 
+         (applyOverlays [ unfree-overlay ])
          ./machines/kcnhub/configuration.nix
          sops-nix.nixosModules.sops
       ];