In your setup the G1100 is being fed from the LAN ethernet of the Google Nest. The G1100 provides LAN traffic over the coax to the set-top boxes. There is no MoCA traffic coming out of the ONT. Only a RF signal so the set-top boxes get video.
If you have a WAN coax connection then the ONT does output MoCA at 1000 MHz which is different than the LAN frequency of 1150 MHz so both signals don't interfere with each other.