I want to be able to use HTML/JS to design my desktop and call APIs. Can I do that with gjs or is it this GTK namespace and GTK-CSS like language only? It would

I want to be able to use HTML/JS to design my desktop and call APIs. Can I do that with gjs or is it this GTK namespace and GTK-CSS like language only? It would be really cool to design the background from the Ubuntu crown to a bunch of widgets of information I use daily.