Worst they can do is deny me entry to the country

Well the worst they can do is

Put me on a no-fly list, terrorist watchlist or even arrest me

Not having jurisdiction has famously never stopped China. Just ask Tibet. Or any country that wants to sail international waters in the south China sea. Or Hong Kong. Or Taiwan.

Lastly, You are correct about China not sharing data with FVEY countries but don't think for a second that they are not sharing that info with Russia, Iran, or any other countries that actively seek to harm.

If a country is going to in some way use my data against me, I'd at least like to know the language and what my rights in that country are.