Proof of personhood: create a DNA reader akin to an external hard drive where a user gives a drop of blood or perhaps some less extreme variant where a microchip implant contains that info, because I really think everyone will have microchips implanted, it's the future of passport and basic identification so most in the future....applications or hardware will have the built-in readers to identify a user using a mix of RFID tech and DNA reader tech...the tech is in existence but the process implementation or widespread use isn't, but soon....
(Inspirating reads: https://compbio.imascientist.org.uk/2014/03/19/why-is-everyones-dna-different/