Ooh, i stumbled across this one site that I wanted to add to my feed reader, didn't find <link rel="alternative"> tags in the header, but a <link rel="https://api.w.org/"> tag. I'm not sure it is their intention to open up the WordPress back-end, but I found how to get the list of articles from it, so added support for it to my own feed-reader: https://github.com/stijnsanders/feeder#feeder
One of the early advantages of Wordpress was precisely its excellent support of all formats of feeds out of the box, back in the hot days of the Rss/Atom feud.
I’ve recently needed to get RSS feeds and a good number of times I can find it via /rss or view the source of the site and search for xml.