If you have a dynamic IP and use regular DNS, NextDNS allows you to ping them on IP change (via an app or a call to their API via a simple curl)

On your cellphone, there's an App that creates a fake vpn

If you're using DNS over HTTP or TLS, you can add an identifier to your requests, so NextDNS knows who you are even when you change IP addresses or you are behind a NAT or CGNAT.

You have to ping it from your machine periodically so it can pick up the new IP, either manually or automatically, or you can use existing dynamic DNS. As for really wide NAT... dunno. May just be incompatible if there's more than one user in your block.