Cambodia - Shanghai - Thailand am I legible for 144-Hour Visa-Free Transit?

Hi,

I have a UK passport. I plan to visit a friend in Shanghai for 4/5 days, travelling from Cambodia - Shanghai - Thailand. These countries aren't on the visa exemption list but my passport is, am I legible for 144-Hour Visa-Free Transit?

To get a 144-Hour Visa-Free Transit do the flights need to be from the same airline and airport in Shanghai?

Thanks for your help.