I didn’t even know about that feature when I was on Reddit. I’ve discovered the “Subscribed” RSS feed on Lemmy that, to my surprise, works without authentication. Anything I follow just stars showing up in that feed automatically. My RSS reader already hides duplicate links but it obviously doesn’t do any kind of analytical comparison of similar links, but it hasn’t been a big deal so far and I’ve joined several, similarly themed communities on Lemmy.