Interfacing a pixhawk on a simulation bench

I am working on a pixhawk (radiolink type) and I need to interface it with a simulation bench. What I have to get in the end is a pixhawk that work exactly as if it was set on a quadricopter drone, but that will actually work with a simulation of all the tools that are usually set on a pixhawk to allow the drone to fly (switch button, buzzer, GPS, ESC, radio controller, etc…) The thing is : I have no idea how to do so. I already know what kind of signals are exchanged between the pixhawk and its environment through its ports (or pinouts) and I know the usual code set on the pixhawk. Can anyone help me please ?

I forgot to say that the simulation bench is made with raspberry pi that communicate with each other and the environment