No, they're not. That's other weird policies specific to your ISP.
With IPv4 + NAT, you have a public IP address. That public address goes to your router. Your router can forward any port to any machine on your LAN. I used to run Minecraft servers from a residential connection on IPv4, it was fine. Never had to call the ISP.
Nope, CGNAT means I need to call my ISP. We now have 2 levels of NAT because the IPv4 address situation has gotten so bad they can't even give every residence its own public IP. If your ISP hasn't adopted it yet its likely they got lucky and bought a ton of IPv4 addresses a long time ago when they were cheap and have decided using them is cheaper than upgrading their network to support CGNAT.
This assumes the ISP allocates a public IPv4 address.
In many countries they don't have enough, so you have CGNAT.