I'm running the software from a Windows PC (big screen) and would very much prefer to control the motion/shooting for the robomaster with a Joystick. It's way more natural than the keyboard+mouse. ANyone figured out how to use a Logitech Extreme 3D Pro with the Robomaster ?

Not possible right now. The PC Windows 10 program can only interface with the mouse and keyboard. From the videos of pilots operating RoboMaster robots I have seen from Twitch livestreams or VOD and Youtube videos, this seems to be the favoured way to control a RoboMaster robot.

Yes, I've seen those videos as well. I've been flying DJI drones for some time now, and got used to using controllers with 2 thumbsticks. However, someone came up with a smarter way using an FT-Aviator. You can do ALL motions with a single hand. I was thinking of something along those lines for the Robomaster. It for sure beats having both hands busy!