For some reason, trying to use aw-watcher-web on Vivaldi fails. No data is displayed in the browser tab. There's no aw-watcher-web-vivaldi displayed in the bucket selector. The same goes for Opera.

I can confirm the extension works in chrome and firefox, with the two buckets aw-watcher-web-chrome and aw-watcher-web-firefox visible.

Chromium pieces of data seem to be collected into the aw-watcher-web-chrome bucket.