If that bill passes the US Senate, the corporate entity for tiktok has 1 calendar year to dissolve the current ownership and establish US company ownership.

I don't think there is anything technical to discuss, its a business/legal issue. If its banned after the year passes and nothing is changed, this might amount to the existing service/site being required to put a popup on its page indicating that a user is coming from US and access is not allowed (similar to some states and a hub of videos). There really isn't any need for anything more technical than that. Yes, users will go around this but I believe the vast majority of users will not bother and will go somewhere else for their digital dopamine fix.

So technically a popup. That is the simplest technical solution that is enforceable by courts staffed with 60-70 year old judges.