Protip: For any free Substack, the feed is at [newslettername].substack.com/feed
I’m going through and unsubscribing from their emails and instead subscribing to their RSS feeds. I haven’t yet found a way to get a feed for paid newsletters, so I still route those from email to RSS with Feedbin.
The process was pretty quick. I went to https://substack.com/library, opened up the console, did a
document.querySelectorAll() for the anchor tag for each publication (my selector will be different than yours so I didn’t include it–yay React!), then extracted the URLs and appended /feed with some quick regex in VSCode. I popped that list into https://opml-gen.ovh/, then imported the OPML into NetNewsWire.