flake: Replace nixpkgs overrides with cleaner ones

flake.nix

@@ -3,7 +3,7 @@
 
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.05";
-    unstable.url = "github:NixOS/nixpkgs/nixos-unstable";
+    nixpkgs-unstable.url = "github:NixOS/nixpkgs/nixos-unstable";
     nixpkgs-2211.url = "https://github.com/NixOS/nixpkgs/archive/34bfa9403e42eece93d1a3740e9d8a02fceafbca.tar.gz"; # old nixpgks for e.g. remmina
 
     nix-darwin.url = "github:lnl7/nix-darwin/master";
@@ -29,28 +29,21 @@
     , nix-darwin
     , nixpkgs
     , nixpkgs-2211
+    , nixpkgs-unstable
     , sops-nix
-    , unstable
     , extra-config
   , ... }@inputs:
     let
       pkgs-overlay = final: prev: {
-        unstable = unstable.legacyPackages.${prev.system};
-        nixpkgs-2211 = nixpkgs-2211.legacyPackages.${prev.system};
-
-        python311 = prev.python311.override {
-          packageOverrides = self: super: {
-            # k5test is broken on darwin, as of 24.05
-            gssapi = super.gssapi.overrideAttrs (old: {
-              doInstallCheck = false;
-            });
-          };
+        unstable = import nixpkgs-unstable {
+          system = prev.system;
+          config.allowUnfree = true;
         };
 
-        tlclient = final.unstable.tlclient.overrideAttrs (finalAttrs: previousAttrs: {
-          # nixpkgs.config.allowUnfreePredicate doesn't work for the unstable overlay, as it is a different "nixpkgs"
-          meta.license.free = true;
-        });
+        nixpkgs-2211 = import nixpkgs-2211 {
+          system = prev.system;
+          config.allowUnfree = true;
+        };
       };
     in
     {