Create a transit gateway in each Region. Create VPN connections from the transit gateways to the on-premises firewall. Create a peering connection between the transit gateways.

Create a virtual private gateway in each Region. Create VPN connections from the on-premises firewall to the virtual private gateways. Configure the on-premises firewall to route the traffic between the two VPCs.

Create a virtual private gateway in each Region. Create VPN connections from the on-premises firewall to the virtual private gateways. Create a VPC peering connection between the two VPCs.

Create a virtual private gateway in each Region. Create VPN connections from the on-premises firewall to the virtual private gateways. Create a VPN connection between the virtual private gateways.