It works also for relays, e.g. https://njump.me/r/nos.lol.rss and this is especially useful for tematic relays. Sorry for hijacking the thread, but I always empathise with RSS lovers!
Oh cool! How often does it update?
Actually, quite randomly, in recent times 😅 @fiatjaf is revolutionising some fetching/caching-related areas right now, so things should improve.
Are there hashtag feeds? Hashtag+ relay? Hashtag+npub?
No, would be a nice option; but I fear that hashtags are too prone to spam for a relay feed, so without a WoT filter or something similar, the rss would be quite pointless. Instead it could work for a npub, or a private/paid relay.