That wouldn't work anyway. IPv6 addresses aren't routable on an address-by-address basis.
Yeah but the digital ID could be the 64bit suffix of the IP. Kind of like that horrendous and moronic idea of using the MAC address as the suffix.
But Mobile IP could do it https://www.rfc-editor.org/rfc/rfc6275
Whether it's workable or not it's besides the point when certainly the UK gov gets it in mind to implement.