Fair, kind of like MSG?

Have you ever messed with KWin scripts? I’m not very familiar, but seems more than capable of exposing window geometry and cursor position.

It relies on Hyprland’s IPC socket. What kind of desktop environment do you use?

Yes it draws under windows, but whether or not you can see it depends on your Hyprland opacity/gaps

I think this one came out best, but there are other effects too: https://slastra.github.io/hyprglaze/demo.mp4