How do such cases immigrate to Hong Kong?

I only know a few things about immigration:

1. To invest in immigration, you need to put a large sum of money in Hong Kong to apply for immigration.

2. Husband and wife reunion (one party is a Hong Kong resident. The other party applies).

3. Children reunite or take care of their parents. (My parents are from Hong Kong, and they are old and have no one to take care of them. Children can apply to become Hong Kong people. Or if the parents are Hong Kong people and the children are in the Mainland, but the children are young, the children can apply to be Hong Kong people. )

4. Introduction by professionals. If you are a talented person needed by the Hong Kong government, have received higher education and have special expertise, you can apply.