Point to Point

If both system are listening then either side can initiate a connection. That’s essentially what a Point-to-Point setup is. Simply translate create two ‘servers’ and add a peer block to each one about the other. They will connect as needed.

This is best done with a routed config where clients who know nothing about the VPN use one side as their gateway for a given network range, and the servers act as routers. I don’t have an example config for this, but if you’ve reached this point you can probably handle that yourself.