https://www.audiobookshelf.org/guides/rss_feeds/

So set the books up in a collection, and add each book. RSS the collection and each book shows up as an episode. I wouldn’t want chapters as episodes, that would be annoying usually.

Since they’re different applications entirely and you wouldn’t use the same client for each, I use Calibre as a kasmweb docker image for ebooks and enable OPDS for it to hook up with my FBreader app. Audiobooks are done with Audiobookshelf and outputs an RSS feed for Antennapod subscription.

I’ve ran email servers for 30 years, I think I got it cased, but thanks for your input.