oh, and that key command for desktop etc is also very useful, apart from when I need the key for something else. That Fn key, for example - I use it all the time for the character viewer, for inserting special symbols and emojis, so there's no way I can re-assign it to something else. And the F3 key is set to Mission Control by default, so there's no need to re-assign that elsewhere as far as I can see.
Have you tried using the "spread with thumb and three fingers" gesture to reveal the desktop?