That's what India did with its UID, Aadhar. The initial days were so bad with security. Anyone and everyone could take the id number and fetch info about you. Now you can lock access with biometrics and even after unlocking it auto locks in 5 minutes. You can also generate a virtual unique id number to prevent fingerprinting across various services. There are still some cases where the security of data seems to be questionable, but it's working there. They also have oAuth support for websites to use aadhar profile. But not many services have integrated with it yet.