A single IPv6 interface can have multiple IP addresses. You can either use your global IPv6 addresses for LAN communication or additionally use a unique local a

A single IPv6 interface can have multiple IP addresses. You can either use your global IPv6 addresses for LAN communication or additionally use a unique local address (https://en.wikipedia.org/wiki/Unique_local_address https://en.wikipedia.org/wiki/Unique_local_address) on that same interface. There's no need for NAT at any point.