I think Lemmy desperately needs to integrate two things:
The ability to search for communities across instances inside of Lemmy (I’m aware of the search option outside of Lemmy, but that’s less than ideal)
The ability to easily search within posts A) in all local communities, B) in all subscribed communities, and C) across all communities in the whole Fediverse. Yes, I’m aware that C) is a huge ask. But I think it’s vital to the success of Lemmy.