Container route all ports except one to one network and the single port to a second one


I’m rather new to Docker albeit I have already set up some virtuallans with macvlan and different private networks within docker compose.

But now I want to route just one port of a container to a different network.

Basically one container should route all its traffic to an openvpn proxy instance but one port should be routed to the hostnet without exposing the whole openvpn network to the hostnet or the whole hostnet to the source container.

Could someone point me to the right direction. Maybe it is obvious but I’m just a bit paralized. Or is that even possible?