I think the cat is out of the bag with Tiktok. If we really think the Chinese government is going to influence ordinary Americans, I'd like to hear why they shouldn't be allowed to do that, and I'd like to hear why they won't just start using Instagram Stories or YouTube Shorts. I get the feeling that old people (like me now I guess) are annoyed that people use Tiktok to come up with absurd pranks that hurt a lot of people and that this platform gives them an audience. But I guarantee that if it's banned, we'll just see the "YouTube Kia Stealing Challenge" or whatever.
The software issue is worrying. If video-sharing applications can be used as malware vectors, that is an iOS/Android bug that needs to be fixed with high urgency. Whatever Tiktok can do, your Verizon app or local newspaper can also do. Do you trust their IT teams to not let malware slip into production builds? I don't. So the OS needs to compartmentalize every app, and disallow wholesale information sharing (no device ID, no access to contacts, etc.; those features are totally unnecessary).
All in all, preventing certain people from having a printing press is against everything our country stands for. Yeah, dumb people can do a lot of harm by publishing dumb things. We balance that risk with with happens when smart people can't publish smart things. Governments have always hated that, but it's always been good for ordinary citizens.