When you’re behind cgnat, the IP doesn’t solely point to your internet connection, but also to one or more others.
It should be possible to request a non-cgnat connection @ your internet provider to make it possible to reach your Homey from internet.
Port forwarding is not recommended though:
https://community.homey.app/t/port-forwarding-and-security/108463
Do you have a specific reason to enable it?