Meta absolutely does business in China.
e.g. https://www.metacareers.com/v2/locations/shenzhen/?p[offices...
https://www.metacareers.com/v2/locations/shanghai/?p[offices...
https://www.metacareers.com/v2/locations/hongkong/?p[offices...
I also assume, like most advertising platforms, they cater heavily to the China export market.