You need to consume the pkgs defined by perSystem using withSystem, something like:
nixosConfigurations.home-pc = withSystem "x86_64-linux" ({pkgs, system}:
nixpkgs.lib.nixosSystem {
inherit system;
modules = [
./hosts/home-pc/configuration.nix
diskoConfigurations.home-pc
] ++ shared;
specialArgs = {
inherit inputs pkgs;
};
};
)