I know you used the prase "China for example believe"
Considering that China has had C19 popping up in various places anyway , the chopping board could mean anything.
European strain, well China has been dealing with returnees as has everyone else for a very long time, and a lot of them.
Roll the covid dice.
It would be many times more likely that its another community spread into a market where it could then amplify through the enclosed nature and high number of contacts, nice comfy temperatures ?
Beijing had not seen much of covid in the early phases, so people may have been naturally a little less cautious after initial emergency seemed to be over , as they felt more protected.
Certainly Whuan market was not the original origin either.
Just a point of spread and amplification, which is why for any other country Who/CDC etc would have sent investigators into the field taking samples to see where it may have entered the market from.
Farming villages supplying the market , etc.
Not an option for China though.