Switch approaches...

flake.nix

@@ -10,20 +10,14 @@
   outputs = { self, gomod2nix, nixpkgs, utils, ... }:
     utils.eachDefaultSystem (system:
       let
-        pkgs = import nixpkgs {
-          inherit system;
-          overlays = [
-            (self: super: {
-              buildGoApplication =
-                gomod2nix.packages."${system}".buildGoApplication;
-            })
-          ];
-        };
+        inherit (gomod2nix.legacyPackages."${system}") buildGoApplication;
+        inherit (nixpkgs) lib;
       in {
         packages = rec {
           default = google-photo-uploader;
-          google-photo-uploader =
-            pkgs.callPackage ./google-photo-uploader.nix { };
+          google-photo-uploader = import ./google-photo-uploader.nix {
+            inherit lib buildGoApplication;
+          };
         };
       });
 }

google-photo-uploader.nix

@@ -1,10 +1,10 @@
-{ config, lib, pkgs, ... }:
+{ lib, buildGoApplication, ... }:
 
-pkgs.lib.buildGoApplication rec {
+buildGoApplication rec {
   pname = "google-photo-uploader";
   version = "1.6.1";
 
-  src = pkgs.fetchFromGitHub {
+  src = lib.fetchFromGitHub {
     owner = "int128";
     repo = "gpup";
     rev = version;
@@ -13,7 +13,7 @@ pkgs.lib.buildGoApplication rec {
 
   modules = ./gomod2nix.toml;
 
-  meta = with pkgs.lib; {
+  meta = with lib; {
     description = "Google photos uploader, written in Go.";
     homepage = "https://github.com/int128/gpup";
     license = licenses.asl20;