I started a little RSS reader in Tilde Friends. You can play with it here, and I'll publish the app in a bit.
It currently just fetches feeds from the client every load (using a CORS proxy on failure). It has some of the old Google Reader j/k/v key bindings. You edit your list of feeds by putting RSS/Atom links in a textbox and clicking save (they're saved in Tilde Friends or localStorage depending on whether you're signed in). That's about it.
But I'm super excited about its potential. I think if I'm a little smarter about caching news, authoring SSB post messages to share or comment on an article, and displaying posts that mention articles, I'm 99% of the way there to feeling like Google Reader. Also my feed parsing needs to be better, but eh. 🤷♂️️