Huh? With IPv6 you get your own IP address, the ISP doesn’t need to know shit about ports. Your address is not behind a NAT anymore, and ports don’t need to be forwarded.

Perhaps you mean the ISP set up a firewall that blocks incoming connections? In which case, maybe you can have that firewall disabled? ISP firewalls and “safe browsing” packages are always shit.

To be honest though there might be some aspect to this I don’t know.