Friendica is still alive and can do this! It's primarily microblogging-oriented, but you can subscribe to any RSS feed too. And users (including RSS feeds) can

Friendica is still alive and can do this! It's primarily microblogging-oriented, but you can subscribe to any RSS feed too. And users (including RSS feeds) can be grouped, so you could have one group "tech feeds", one group "cat accounts" etc.