as a path that I can have broadcasters input into OBS, to generate an overlay?
The goal is to have another page on the extension that can show on-screen alerts and the easiest way i can think of is to host the browser source as the live config page or the video overlay page.
If you want to display alerts in a Browser source, use an entirely separate page rather than trying to misuse pages intended for displaying a config. This could even cause you to fail Extension review if the reviewer goes tot he live config and see it displaying alert graphics instead of being a config page.
And if you try to use the video overlay, well they why would it need to be a browser source as that’s what will already being displayed to users as the overlay, so you would be duplicating graphics by having both users display it and your browser source.