Presumably by asking the Chinese authorities directly? We have near instantaneous global communication these days - that's how I'm conversing with you right now.

There's also AIS

https://www.marinetraffic.com/en/ais/home/

Of course enabled by the very tech you mention.

There is a pretty huge amount of ship and satellite tracking these days

You’d just lie about which ship it was on.

While it's still in the shipping container with a GPS tracker on it?

I've very briefly worked with a team that was responsible for satellites that track ships and their AIS data, including trying to identify ships spoofing AIS though various means. (It was civilian, a university group, but I'm sure states have similar and more)