You might be interested in feed2maildir [1], which saves feeds in maildir format so you can use all your favorite mail clients and index with notmuch. That way, you aren't dependent on another centralized privacy-invasive proprietary SaaS walled garden being online and running without major changes.
I've been planning on transitioning from my current TUI RSS reader (Newsboat) to a maildir-based CLI with notmuch filters for a while; I might give it a shot next weekend and post some of my notmuch filters for RSS.
My email client is actually much more powerful than most readers in letting me capture read status and labels / sorting.