I use this:

{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.05";
    home-manager.url = "github:nix-community/home-manager/release-25.05";
    nixpkgs-unstable.url = "github:NixOS/nixpkgs/nixos-unstable";
    nixpkgs-unfree.url = "github:numtide/nixpkgs-unfree";
    nixpkgs-unfree.inputs.nixpkgs.follows = "nixpkgs-unstable";
  };

  outputs = {
    self,
    nixpkgs,
    home-manager,
    nixpkgs-unstable,
    ...
  } @ attrs: {
    nixosConfigurations.laptopname = nixpkgs.lib.nixosSystem {
      system = "x86_64-linux";
      specialArgs = attrs;
      modules = [
        ./configuration.nix
      ];
    };
  };
}

and my configuration.nix includes everything for me