The current problem is, TeamViewer currently won't transmit Joystick input (over LAN). To do this I think TeamViewer would need to make the remote controlled win 10 PC think that there is a Joystick connected to it.
I've the same problem. Have a friend that I help out with his computer using Teamviewer. Now I'm running MSFS 2020 and want to teach him about aircraft and flying. How can I get teamviewer to recognise the Logitech joystick so he can operate the aircraft on my pc remotely, mouse and keyboard inputs work , but not the joystick . ??. He does not have MSFS 2020 installed on his computer as yet , a little to expensive at this stage.