Huh???

Honestly I don’t see your problem, a nuance? Sure! An unsolvable problem? For sure not.

If you want to have your system reachable from the Wan then you will need a domain name. If you have a domain name then it is needed to be resolved by a dns server.

If there is a dns resolver then you would able to update it dynamically every time your ip changes.

True that the time alive of the dns records must be low enough to ensure that an ip change does not let your system down for an unacceptable amount of time.