The migration app of choice appears to be .. xiaohongshu, or "little red book". I'm guessing this won't last since it wasn't intended to have lots of Westerners using it and neither government is going to be happy with that scale of unfiltered contact between ordinary Chinese citizens and US citizens. In the meantime, it's the place for Luigi Mangione memes.
As a casual observer, I don't understand why YouTube Shorts isn't the obvious successor? The UI is better than TikTok ever was and a lot of the most popular creators are already mirroring their content there?
Reels needs to be more disconnected from Facebook for it do anything similar.
Why do you say the Shorts UI is better? It seems exactly the same to me.