Lemmy is not an ideal format for book clubs because it doesnt nicely handle long, drawn out discussions under a single post. The algorithm is designed to decay with time, so a post rises to the front page exactly once. Moreover there is no Watch feature to get notified for new activity under a post. So we just have to deal with people manually checking the thread through the week.

There is an ActivityPub version of Goodreads called BookWyrm but it’s barebones. But it seems like a more natural technology for hosting book clubs, even if there is not a book club implementation there yet. Under a book page there could be scheduled events like weekly discussions.