Technically they work, because I get a Keypress Event from them - but normally you got this android overlay and that is not appearing for me (I have to handle the volume internally by adjusting SoundEffect.MasterVolume on keypress).
I am in Full-Immersive-Mode, maybe that has something to do with it?
So monogame is actually handling the volume buttons and orders to display the android volume control in MonoGameAndroidGameView - it just looks like the KeyUp/Down of is somehow not triggered in my case?
When I actually subscribe to the KeyPress-Event of the view and do the above code manually, everything works. But KeyboardState is also populated so (which happens also in MonogameAndroidGameView.KeyDown) - so this puzzles me.
Maybe it is important to mention, that I do not have a usual layout in place, and the gameview is a subview in my layout.
Maybe someone can give me a hint, if there is a more elegant solution than just duplicating the event-handling from the GameView?