persona-field, bytes
name-first: 14
name-last: 14
name-middle: 16 delete for more space
initial-middle: 1 instead of name-middle to save space
country-code: 3
address-street-1: 16
address-street-2: 12
address-city: 16
address-postal-code: 8
completed-at: 4 can be stored as uint32, thus 4 bytes
birthday: 4 can be stored as uint32
UUID could be hash(first, last, birthday). This is farily unique and fairly interoperable across different ID documents and providers. However, it is vulnerable to dictionary attacks, so should never be made public except with extreme caution.