I decided to see if they could be sourced reliably at any volume from the meta tags of a stream of links, which are easy to find. Long story short, that did work very well. I used the Bluesky firehose as the stream of links.

The repo has a script that narrows the firehose down to just a "fountain" of RSS feeds and their metadata. There's also a .tsv with about 30,000 entries I got from running the script on and off over a few days.

https://github.com/tfederman/fountain-of-rss/

p.s. What's good in the RSS tool/reader scene in 2025?