The unsafe_hash option is unsafe only because it doesn't afford mutability protections.  This can be mitigated with selective immutability.

@dataclass
class Person:
    ssn: int = field(immutable=True)
    birth_city: int = field(immutable=True)
    name: str      # A person can change their name
    address: str   # A person can move  
    age: int       # An age can change

This would generate something like this:

   def __setattr__(self, attr, value):
      if attr in {'ssn', 'birth_city'} and hasattr(self, attr):
           raise TypeError(
               f'{attr!r} is not settable after initialization')
      return object.__setattr__(self, name, attr)

A number of APIs are possible -- the important thing to be able to selectively block updates to particular fields (particularly those used in hashing and ordering).