I now have the need to display some ToolbarItems in a disabled state. The icons (no text) should be visible, but greyed out.
Currently I'm mostly interested in an iOS solution. My app is not released on the other platforms yet.
In my AppDelegate I set
UIApplication.SharedApplication.KeyWindow.TintColor so that all Titles and ToolbarItems are tinted. So even if I change the image to a disabled one, because of this automatic tinting, the color of the image is replaced by the
TintColor for all icons.