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?

But what all is needed for tracking? AI-based metadata extraction from the video and metrics of how long the user watched the video before swiping or rewinding or stuff? That can all be done at the instance level. I’d imagine the bigger issues is the engineering involved in the app content creation tools, and the costs of data storage for all of those videos and bandwidth for distributing them, something TikTok currently just foots the bills for. Arguably an open source equivalent wouldn’t have the privacy stigma around it, right?