I don’t know anything about the google mesh to offer any advise on its config.
But if you have a standard phone line with a home hub plugged in you must have FTTC.
You maybe doing a double NAT, but I don’t know.
I would see what the IP address is of your core and see if that’s on your home hub, if that’s the case setup a port forward on the home hub.
The other option to port forward is to use Tailscale as a number of us have done which is a vpn type access rather than a port forward, this needs a basic skill level to understand.