Whether Chinese policy has been effective depends on how many people have died and to what degree they had to tradeoff their economy for it. But without authoritative numbers on the table for discussion, we're just pumping text around the web.

For most of the duration of Covid I actually worked for a large company that maintains large (hundreds if not thousands of people) development workforce in Shanghai. I left in November 2021.

NONE of them got sick, as far as we know. Some of them are good friends of mine and in safe, private conversation confirmed the same.

There were some lockdowns, but it seems they were largely precautionary.

No, it is not. What happened initially and what is happening now are two completely different things. Nobody disputes that it is no longer possible to beat the virus. Even if China did beat the virus completely they would still be receiving fresh cases from abroad.

China is in a difficult situation now, because their vaccines are completely ineffective for Omicron, because their population is so densely packed and has low health standards and because their health system is much more fragile.

This is just hand waving. You’re basically saying we could have beaten Covid if: a) China locked down before the virus left their country, b) if their vaccine prevented Omnicron [note: no vaccine does], c) China wasn’t densely populated, had a healthier population and better healthcare system?