Hi,
I would question if AEM is designed to store PII data in the repository. Of course you can store that kind of data, but then you have to take care of encryption yourself (that means use a proven crypto library!).
For example, if you consider the gender of a user as PII and want to store it encrypted in the repository (in the user profile), you need to make sure, that your code does a transparent encryption/decryption when accessing it. That works well as long as only your code is accessing that. If you want to encrypt the name of user as well, you also need to make it work with the JCR/Jackrabbit Usermanager, which is capable to read and write that as well. Not sure how I would implement that.
What's your usecase?
Jörg