Unity - InputSystem - Gamepad access etc.

2020-09-29 high level description:

open the project settings

enable preview packages

open the Package Manager

select the filter Unity Registrations 

Install the InputSystem Package

go to your project Assets folder of the inspector

choose Create the right mouse button click

choose Input Actions - this will add the InputSystem asset 'New Controls' to your project.

'New Controls' - rename it with Gameplay for instance

Doubleclick on 'Gameplay'

The Window to add the actions and bindings comes up.

Anchor the window next to the Console window etc. for a quick access.

Add a Input Map called 'MenuControl'

Add a action to the 'MenuControl' called 'moveLeft'

Add a bindung or more bindings to move the menu cursor finally to the left - so just add a binding of the left arrow key to this action 'moveLeft'.

Notice the save checkbox in top of the window. Activate it for saving. 
Also check the properties of the created asset. Doublecheck the checkbox overthere "create class".
This will generate a new proxy class for the inputSystem called 'Gameplay' here.

In your unity application create an instance of this class.

Important is to call the .enable() method of the instance of such created Input Action Asset. Just add the call of the .disable() method of the object in the OnDisable() method of the hosting gameobject.

To the instanced object register callbacks for each action of the input system map 'MenuControl' of the input system 'Gameplay'...

And / Or add direct request to the Keyboard.current or Gamepad.current objects if any key or button is pressed.