But maybe I have missed an obvious marker along the path.
Leaving more as a note for myself, some annotation rss tricks from Chris Aldrich
Notes on this blog
https://hypothes.is/stream.rss?wildcard_uri=https://cogdogblog.com/*
Also explore https://annotations.lindylearn.io
e.g. https://annotations.lindylearn.io/domain/cogdogblog.com