You don't to have to use realistic desert backgrounds or screen caps with actual deserts. Using one of the color palettes only is okay. Maybe you can try adding sandy or dusty effects to fit the theme. A few of the entries so far have abstract desert inspired backgrounds.

If you could please don't make icons that show completely different environments, or non-desert weather or animals, like stock icons of whales or something.

I'm glad you like that palette, thanks! :) I modified from it from this one.