only apply overlays where needed

modules/default.nix

@@ -10,14 +10,8 @@
     ./vm
   ];
 
-  nixpkgs = {
-    overlays = [
-      inputs.nur.overlay
-    ];
-    config = {
-      allowUnfree = true;
-    };
-  };
+
+    nixpkgs.config.allowUnfree = true;
 
   environment.sessionVariables = {
     NIXOS_OZONE_WL = "1";

modules/niri/default.nix

@@ -1,5 +1,10 @@
-{ lib, config, pkgs, ... }: lib.mkIf config.withNiri {
-  programs.niri.enable = true;
+{ inputs, lib, config, pkgs, ... }: lib.mkIf config.withNiri {
+  nixpkgs.overlays = [ inputs.niri.overlays.niri ];
+
+  programs.niri = {
+    enable = true;
+    package = pkgs.niri-unstable;
+  };
 
   home-manager.users.${config.username} = {
     home.packages = with pkgs; [

modules/user/default.nix

@@ -5,7 +5,6 @@
   ];
 
   config = lib.mkIf config.full {
-
     # Audio
     security.rtkit.enable = true;
 

modules/user/firefox.nix

@@ -1,4 +1,5 @@
-{ lib, config, pkgs, ... }: lib.mkIf config.full {
+{ inputs, lib, config, pkgs, ... }: lib.mkIf config.full {
+  nixpkgs.overlays = [ inputs.nur.overlay ];
   home-manager.users.${config.username} = {
     programs.firefox = {
       enable = true;