you know the drill at this point

modules/nixos/shells/zsh/default.nix

@@ -0,0 +1,16 @@
+{ inputs, config, lib, pkgs, namespace, ... }:
+let
+  inherit (lib) mkIf mkEnableOption;
+
+  cfg = config.${namespace}.shell.zsh;
+in
+{
+  options.${namespace}.shell.zsh = {
+    enable = mkEnableOption "enable zsh shell";
+  };
+
+  config = mkIf cfg.enable {
+    # Enable completion for sys-packages:
+    environment.pathsToLink = ["/share/zsh"];
+  };
+}