I think that your question is more related to the way how to connect some on-premise environments to GCP networking system that gathering Google cloud instances or resources throughout VPC connection model.
Admitting the fact that GCP is actually leveraging different approaches for connection methods within a Hybrid cloud concepts, I would encourage you to learn some fundamental principles of Cloud VPN as a essential part of performing secure connection between particular VPN Peer Gateway and Cloud VPN Gateway and further creating a VPN tunnel between parties.
I guess there is even dedicated chapter in GCP documentation about Data Fusion VPC peering implementation that might be helpful in your user case.