Add logic for native-cross

configuration-native.nix

@@ -0,0 +1,11 @@
+{ config, pkgs, lib, ... }:
+{
+  config = lib.mkIf (pkgs.stdenv.buildPlatform == pkgs.stdenv.hostPlatform) {
+    environment.systemPackages = with pkgs; [
+      meld
+    ];
+
+    programs.git.config.merge.tool = "meld";
+  };
+
+}

configuration.nix

@@ -1,6 +1,6 @@
 { config, lib, pkgs, ... }:
 {
-  imports = [ ./overlays/packages.nix ];
+  imports = [ ./overlays/packages.nix ./configuration-native.nix ];
   nixpkgs.config.allowUnfree = true;
 
   nix.settings.extra-experimental-features = "nix-command flakes";
@@ -37,7 +37,6 @@
     stdenv.cc
     stdenv.cc.bintools  # bins but not manpages included in stdenv.cc
     patchelf
-    meld
 
     (python3.withPackages (p: with p; [
       virtualenvwrapper
@@ -94,7 +93,6 @@
         core.editor = "nvim";
         init.defaultBranch = "main";
         blame.markUnblamableLines = true;
-        merge.tool = "meld";
         credential.helper = "store";
         url."ssh://git@".insteadOf = "git://";
       };