cPanel on GCP - External/Internal IP mapping

Id like to at any point, provide an external IP to a single VM (single zone) running WHM for the use of a "dedicated ip" that is assignable to a domain within WHM. Id also like to have a single external IP address always assigned to the VM for use as a "shared" IP within WHM. This is easy enough to make the IP allocations in WHM. However - Whats the best way to approach this? What is the routing and mapping functionality that I need to implement specifically within GCP? I've explored the use of cloud NAT, however this would seem to only be effective for outbound traffic. Thanks