If you're unfamiliar with Surf Social it's a pretty simple concept: It allows you to make feeds that incorporate RSS, BlueSky and Mastodon accounts (and thus some Threads accounts), podcasts (yes, also RSS but formatted appropriately), inter-network hashtags, and YouTube (and maybe more, I don't have an exhaustive list). Peertube also works via RSS.

I suppose these are all things that you can technically get with an RSS reader (can you follow bsky with RSS?) but really it has more to do with the way the content is formatted, as well as the fact that I can share feeds, and browse others' feeds.

You can also sign in with bsky/threads and comment using those accounts.

It's very cool, and I've been having a lot of fun with it, but it is and will remain closed-source. The monetization strategy is unclear but it sounds like they're going for a sort of Patreon-style approach, in addition to potentially paid ads. And also you cannot use it without a Surf account, which I do not like.