Hi @Frank1, a while ago I created a Chromium browser extension that enables the ability to automatically navigate to and cycle through browser tabs that are playing audio. I just published it on Github:
You could install this extension on Vivaldi and Brave and then with a little scripting in BTT you could achieve your goal, if I'm understanding it correctly.
Unfortunately Vivaldi does not expose the speaker icon in the tab titles, thus for Vivaldi I'm not sure whether there is a simple solution, so there you might need an extension.