The mainland immigrated to Hong Kong and then to Canada.

Dual nationality in Hong Kong means that China nationality and foreign nationality coexist in Hong Kong. . However, you must hold China nationality first, and then become a foreign nationality.

You can't do this. . Because you are a mainlander, you become a Canadian citizen. For Hong Kong, you are Canadian. . . You can come to Hong Kong through the relative immigration or talents program and get a Hong Kong permanent identity card after seven years. But if you want to acquire China citizenship in Hong Kong, you must give up your Canadian citizenship before you can acquire China citizenship in Hong Kong. . .

If you want to be a Hong Kong resident, you can. You must rely on your high education or rich work experience, and you are short of talents in Hong Kong. You can apply for a talent plan to work in Hong Kong. . Or if you have family members in Hong Kong, you can come and settle in Hong Kong as a dependent. . After living for seven years, you can obtain Hong Kong residents and apply for permanent residents. . But you are still Canadian. . Because Hong Kong residents and Hong Kong permanent residents have nothing to do with nationality, they can be of any nationality. . .