Is it an ID card or a one-way permit after the account is moved to Hong Kong?

After the account is moved to Hong Kong, it is a one-way permit.

People's Republic of China (PRC)-Hong Kong-Macao Pass (usually called One-way Permit) is a document issued by the relevant public security department to mainland residents who have relatives in Hong Kong or Macao to settle in Hong Kong or Macao.

Mainland residents can move to Hong Kong through this one-way permit and obtain Hong Kong status, but they must cancel their domestic identity cards and household registration, so they are called one-way permits. If you need to go back to the mainland, you can apply for a home visit permit.