To be quite honest, I don't have that much knowledge about IPV6, but as far as I know, unlike IPV4, with IPV6 each device receives an individual Public IP, so there is no need to do port forwarding.
In IPV4 we receive a single Public IP address, this address is assigned to the router and the router needs to do port forwarding to direct the flow that arrives at it to the appropriate device.
That's what I understand, but I could be wrong.
My intention here is to enable IPv6 on tvheadend so that I can access it from the internet, since the company put me on CGNAT I can no longer access my server from the internet, only on the local network.