Feature: Be able to have the OpenVPN "IPv6 Tunnel Network" as a dynamically assigned IPv6 Prefix from the DHCP-PD allocation. This would function just as the LAN and OPT interfaced get their /64 from the tracked interface.
Justification: If the provider IPv6 assignment changes, you must go back and manually reconfigure the OpenVPN IPv6 /64. This feature would allow it to change dynamically, just as the LAN and OPT interfaces do. Eliminating a potential service affecting situation.