Apple Intelligence for iPhones bought in Hong Kong

1. For iPhone 16 (Pro/Pro Max included) bought in Hong Kong, which AI engine is likely to be used for Apple Intelligence (e.g. ChatGPT, Baidu AI)?
2. Can the AI engine be disabled when I am using functions of Apple Intelligence?
3. Will I be able to use ChatGPT as my Apple intelligence engine if I am outside HK/mainland China? (for phones bought in HK)

Much appreciated.