I'm using shared networking. I kind of like having the Windows on NAT, but I would like a way to route traffic from the GuestOS to the HostOS.
Sure. I have a PostgreSQL database running on the host OS (macOS, IP 192.168.x.x) that I want to access from the GuestOS (Windows 10 IP 10.something). I don't want to make the GuestOS an equal rights citizen on my LAN, but I want to have a route for the GuestOS to reach the PostgreSQL database on the host.
I did not check (and I suspect it would work) but that would not help me. I do not want to use bridged mode because that makes the client OS a fully active actor in my LAN and it will be able to try to connect to all systems on the LAN. I want the client OS isolated. Except that I want an exception of the isolation with a route from client OS to host OS only so the client can access a service on the host. It would be enough to be able to do a ping from client OS to hostOS while in shared network mode. If that works, I can get the rest to work. Note, the host is configured to answer ping, so it is a good check.