Revert approach...

flake.nix

@@ -9,13 +9,20 @@
 
   outputs = { self, gomod2nix, nixpkgs, utils, ... }:
     utils.lib.eachDefaultSystem (system:
-      let inherit (gomod2nix.legacyPackages."${system}") buildGoApplication;
+      let
+        pkgs = import nixpkgs {
+          inherit system;
+          overlays = [
+            (final: prev: {
+              inherit (gomod2nix.legacyPackages."${system}") buildGoApplication;
+            })
+          ];
+        };
       in {
         packages = rec {
           default = google-photo-uploader;
-          google-photo-uploader = import ./google-photo-uploader.nix {
-            inherit nixpkgs buildGoApplication;
-          };
+          google-photo-uploader =
+            pkgs.callPackage ./google-photo-uploader.nix { };
         };
       });
 }

google-photo-uploader.nix

@@ -1,11 +1,11 @@
-{ nixpkgs, buildGoApplication, ... }:
+{ pkgs, lib, ... }:
 
-with nixpkgs.lib;
+with pkgs.lib;
 buildGoApplication rec {
   pname = "google-photo-uploader";
   version = "1.6.1";
 
-  src = nixpkgs.fetchFromGitHub {
+  src = pkgs.fetchFromGitHub {
     owner = "int128";
     repo = "gpup";
     rev = version;
@@ -14,7 +14,7 @@ buildGoApplication rec {
 
   modules = ./gomod2nix.toml;
 
-  meta = with nixpkgs.lib; {
+  meta = {
     description = "Google photos uploader, written in Go.";
     homepage = "https://github.com/int128/gpup";
     license = licenses.asl20;