> how do you think companies which has international business operate in China? how they communicate with their clients how they advertise in YouTube?

I actually happen to know. They have subsidiaries in HK and elsewhere.

> how developers of Microsoft in China pull their docker images?

That their employees use VPN is true. I did not write precisely. iirc like in Russia using VPN for "technical purposes" is actually legal. Using it to access censored information (which is what we are talking about) is not. So if you are not an IT worker and have no excuse and you use VPN to use Twitter... THEN police would have to look the other way. How often does that happen? Probably almost never because people would not shout about the fact that they do it