> ByteDance can't sell advertising in Canada.
I'm not sure I follow (maybe there's other details you know about that aren't in the article, or I missed it). I don't think there's anything preventing a Canadian company from paying a foreign company for ads? In theory I'd have to self-assess PST maybe but I order stuff (both physical and digital) from foreign companies with no Canadian presence on a pretty regular basis.
Small credit cards transactions fly under the radar. But a big business with a big budget won't be able to advertise on Tiktok. That's why companies establish these offices. They are essentially import/export offices that allow the flow of money out of said country.