Haven’t heard of them before, I know there are some tools to generate feeds by selecting elements on the page and then the tool figures everything. One of the tools I tried didn’t work for the site I needed it for and so I just wrote it myself, mostly for fun.
Feed43 is based around pattern matching - it mostly assumes a well-structured HTML document with predictable tags, and it's that method for every site.
You seem to have some sort of custom plugin architecture, I guess?
Exactly, mine is really only focused on sites that are either hard to scrape (login, blocking, not well formatted,...) right now. So either site you want to integrate requires a custom plugin. It's pretty niche but the repository can be found here in case anyone is interested: https://github.com/dewey/feedbridge
Somewhat related, I built a small tool to scrape sites with no feeds and generate one: https://feedbridge.notmyhostna.me/