I've been using an app called Summit for Lemmy, and it feels very RiF-esque. RiF was the only way I used Reddit, and it's made the transition very easy. In fact, in some ways, I feel it's done some quality of life stuff even better than RiF did, like color coding comment chains, which makes it easier to keep track of who's responding to who.
I use Feeder, and most sites I'm interested in have RSS feeds discovered if I plug in just the URL of their front page. Other sites can be a bit more of a pain, bit you can often just add /RSS or /feeds to the URL and the readers will work it out.