Direct access (without MAVLink) has been in development for a long time now. There is a Windows IoT SDK in progress here: GitHub - emlid/Navio-SDK-Windows-IoT: Navio SDK for Windows IoT The forum thread is here: Navio SDK for Windows IoT - #61 by CodeChief
If you want to work in “companion computer” mode (one RasPi Linux with Navio and the Win10 connected to that) a loopback ethernet cable on the drone is probably the most efficient. Or you tie one serial on each board together. This is the only solution which works today, until the SDK is finished.