It’s unclear there is support for that. I’ve worked on privacy issues. Virtually nobody calls in support of them.
This, on the other hand, is a national security bill. Every elected I know is being inundated from both sides.
The problem is that our first-past-the-post voting system naturally prioritizes engagement over everything else. That's why our elections are always about controversy, and never about progress.
Edit: I stand corrected, they are bound by our laws, but it's orders of magnitude easier to enforce those laws on a company based in the US than a company based in China.
Theoretically, yes. But the US isn't a police state where their activities would be constantly monitored in great detail for compliance. There's a lot they could do under the radar, and a lot of groundwork they could lay for some future inappropriate action.
This is how EU rules apply to US tech companies. US rules for Chinese tech companies is no different in principle.
IMO however the problem isn't privacy, it's being able to stick a thumb on the algorithmic feed and control the information consumption of a slice of society. And TikTok isn't the only problem, it's broadly applicable across consumer tech.