alt Hacker NewsMeta 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.
I don't think their social networks are allowed in China.
From your link it looks like they might do R&D for Oculus in China (but may not even be able to sell it there due to the data-collection tie in required).
Not sure what you mean by catering to the export market. b2b sales would be just as restricted as sales to consumers.