If I immigrate, can I still use Alipay account? The information has changed. What if the number is stolen?

Can be used. However, if you really change your nationality and cancel your account in China, Alipay will prompt that the information is wrong and the account is still there, but you can't use the payment function.

You can register a new one by borrowing the identity of relatives and friends, or you can contact relatives and friends to help you buy things and send them to you.

You'd better register a new number and use your new identity to register Alipay International Edition. But if you want to buy things online, the price may be higher than that in China (and the freight is naturally high).