What we need is widespread IPv6 support. Portforwarding isn't the problem. The terrible UX and the existence of CGNAT (carrier grade NAT) is.
My ISP blocks such connections on LTE mobile network. Maybe so you don't pay a lot of money for traffic if people DoS you? It doesn't make sense, since ICMP ping packets are allowed.
Well, it's either my ISP or the android phone I have. Does android have any firewalls enabled by default?
You unfortunately need ubiquitus IPv6 support to actually rely on IPv6, which isn't going to happen anytime soon.
So you really need to consider the benefits of dual stack v4 and v6 simultaneously within the same group of players. Might be useful, but it adds a whole heap of complexity.
The problem is deploying CGNAT without also providing IPv6 as an alternative.