I use gitea

But how is that a different problem than mastodon or Lemmy or friendica face? What makes TikTok different?

I mean network effects are real. You always have a hard time moving users over to a new network platform. Are you saying that anyone using TikTok right now arguable does not care about privacy at all so would be unlikely to see the value of federated decentralized apps?

Well you don’t have to subscribe if you don’t like it