Getting HK or Macao PR is almost impossible - you have a better shot getting Shanghai or Beijing hukou. It's also a grey area - dual nationality is "permitted", not "allowed", and this policy can easily be revoked given how unstable HKSAR and Macau's governments have become

As such, it is an edge case or rounding error - especially in the Chinese American community. With the amount of effort it takes to get HK citizenship, you may as well take Canadian or American citizenship and try to break Chinese nationality law by lying about not having American citizenship (but they are cracking down on this)