Author of Win4Icom and Win4Yaesu here. Win4 has built in virtual radios that can connect to any software on the market except for apparently your software. The reason being you do not include virtual com ports in your enumeration of the ports.
There are over 12k users of my products and you will miss out on supporting the best control app out there.
We have plans to add support for virtual coms ports, especially in the desktop app when its released. However with that said, I’ve currently been able to get our cat control app working with VPSE without any issues. Once the virtual com port is created it will show up in the list of com ports. We will be adding this support in the near future.