Retrieve public IP of another EC2 instance in Saltstack formula

I'm setting up VPN nodes with Cloudformation and provision them with Saltstack. Let's call them left and right node. When provisioning the left node I need to know the public IP of the right node and vice versa. Is there a way to retrieve the IP of another EC2 instance in Saltstack formula? Both instances have tags associated with them.

Or is there a different way to achieve this? I would just like to omit any hardcoding.