Honestly might be an interesting way to do a tiktok-like. Video hosting is super expensive if its centralized; it takes up so much space and has to be super compressed. If instead everyone who creates content also ran their own instance, then federated with a big normie instance, it could conceivably work. The creator would host their content forever, the normie instance could host it for a short timespan to boost visibility, then viewers follow the normie instance and any creators that they want to see more of (and have archives of their own videos)
If instead everyone who creates content also ran their own instance
this can't be it, sadly. All of the best content creators on tiktok are not in the position financially or technically to host an instance of anything, let alone configure and maintain it. This is especially true for journalism, politics, and ordinary goofball content, which in my mind are three things tiktok is best at and are critical to its value. There has to be a way for someone with no technical background and no money to share their voice if this is to be "federated tiktok".
Journalism: the instance is for the newspaper/radio/TV/... not just one journalist.
Politics: party instance.
That reduces the load. And other areas can do the same. A game development company can have one instance for everything and everyone related to the company.