Tangentially on this note, if anyone is interested, I can produce a list of every RSS feed known to the marginalia search crawler. It's a pretty noisy list, but any thing I can do to help the spread, discovery and adoption of RSS I'm happy to help with so just let me know. I a tool in place to export this data to help power the experimental RSS preview feature[1], but haven't had the inspiration to do much with that…
The data is, as mentioned, pretty noisy. It's a best-effort guess as to which is the canonical RSS feed for the particular domain. There doesn't appear to be any convention for specifying this, so when there's multiple a fair bit of guesswork is involved. Expect a fair number of dead URLs, lots of spam from CRMs that generate uninteresting feeds.