finally got hyprland plugins to work (however only from nixpkgs repo)

modules/scripts/killall.nix

@@ -0,0 +1,19 @@
+{ writeShellApplication, hyprland, jq,... }:
+
+writeShellApplication {
+	name = "custom-killall";
+	runtimeInputs = [
+		hyprland
+		jq
+	];
+	text = ''
+  active_workspace_id=$(hyprctl activeworkspace -j | jq -r '.id')
+
+  hyprctl clients -j |
+    jq -r ".[] 
+      | select(.workspace.id==''${active_workspace_id}) 
+      | select(.focusHistoryID!=0) 
+      | .pid" |
+    xargs -r kill
+'';
+}