Depends what you are trying to do with that data, exactly. Can you tell us how you’ll use it later?
While you can store some additional details in the JWT’s metadata, that is not a good “general purpose” storage place, so I’d suggest that you create a signup form that populates your database (and your code can access it to pull up those details for logged in users afterwards), and don’t try to use identity to store the data, since we don’t have a good method for you to export it (vs your database, where you control its provenance).