Today the first of Feb is Global Switch day, Spread awareness of the Fediverse in your communities.
There's also StoryGraph - it's not federated, but ran by a tiny UK company, but seems pretty popular. I like the content warnings feature and stuff like readers rating the pacing and moods of the books, which is then displayed with graphs on the book page, but they have also introduced some AI features :/ (fortunately opt-in)