Your organization has a hub and spoke architecture with VPC Network Peering, and hybrid connectivity...

Create custom routes at the Cloud Router in the hub to advertise the subnets of the VPC spokes.

Create custom learned routes at the Cloud Router in the hub to advertise the subnets of the VPC spokes.

Create custom routes at the Cloud Router in the spokes to advertise the subnets of the VPC spokes.

Create a BGP route policy at the Cloud Router, and ensure the subnets of the VPC spokes are being announced towards the on-premises environment.