Ok, resigned that we need home-manager and system-manager seperate. Working niri

system-manager/flake.nix

@@ -0,0 +1,34 @@
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+
+    system-manager = {
+      url = "github:numtide/system-manager";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+
+    nix-system-graphics = {
+      url = "github:soupglasses/nix-system-graphics";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+    home-manager = {
+      url = "github:nix-community/home-manager";
+      inputs.nixpkgs.follows =  "nixpkgs";
+    };
+  };
+
+  outputs = { self, flake-utils, nixpkgs, system-manager, nix-system-graphics, home-manager }: {
+    systemConfigs.default = system-manager.lib.makeSystemConfig {
+      modules = [
+        nix-system-graphics.systemModules.default
+        ({
+          config = {
+            nixpkgs.hostPlatform = "x86_64-linux";
+            system-manager.allowAnyDistro = true;
+            system-graphics.enable = true;
+          };
+        })
+      ];
+    };
+  };
+}