CGNAT isn't imposed by governments, it's imposed by address space exhaustion in v4. v6 fixes it by having enough address space that NAT isn't needed.
Governments share some responsibility here for not mandating a move to v6, leaving everybody in "wait for other people to go first" mode, and one might ask why they've done that but the answer is mostly that governments don't usually get involved in the Internet at that level.
I've not seen an ISP do CGNAT on v6, even when they're doing CGNAT on v4. This makes sense because CGNAT is expensive and doesn't have any benefits for the ISP except for dealing with address space exhaustion. If they wanted to prevent inbound connections then all they would need to do is firewall them.
>If they wanted to prevent inbound connections then all they would need to do is firewall them.
Note that this already happens to an extent. Some ISPs try to protect their users from UPNP attacks and block certain inbound ports. On the outbound side, many ISPs ban port 25. ISPs could have easily claimed security and limit inbound connections far more - but the reasons for these limits are apparently money+security and not a secret government mandate, so they didn't limit everything.
Governments share some responsibility here for not mandating a move to v6, leaving everybody in "wait for other people to go first" mode, and one might ask why they've done that but the answer is mostly that governments don't usually get involved in the Internet at that level.
I've not seen an ISP do CGNAT on v6, even when they're doing CGNAT on v4. This makes sense because CGNAT is expensive and doesn't have any benefits for the ISP except for dealing with address space exhaustion. If they wanted to prevent inbound connections then all they would need to do is firewall them.