Other than the “controls” interface ( aka joystick ) there is no other way to interact with the sim but using “Simconnect”
I am linking here to an versatile version of “joystick - buttons” or “only buttons” only “analogs” interface that is based on PIC 2550 . Works ok in MSFS.
Post 11/12.
And joysticks only communicate one way ( input to sim , as I understand it)
So , the interface is a must. Like mentioned here before.
But it should not be to difficult to program one yourself. Not at all. Definitely not too much work ( looking at your gorgeous panel design … should be no problem )
Such an interface programmed in C# and using the Serial port to comunicate ( two ways ) with arduino, will result in a nifty little executable that will but use any resources on the Pc running MSFS.
And you will be able to interact not only buttons but dialed values of your panel ( Traffic would be only comma separated strings according to your own protocol., for example)
I am writing here mainlly to encourage you to program the interface yourself. It is really not that difficult.
MSFS Simconnect is, apart from little differences , same thing as in FSX -Prepar … So there is tons of info out there on how to go about it.
Hope it helps.
Greetings.