On mobile devices they could be used for a long time already: dynamic wallpapers. While iOS only features colorful moving bubbles on the screen, Apple has now introduced a dynamic background image of the Mojave desert with macOS Mojave. This will show the desert depending on the local time - either by day or by night. In addition there is a - in my eyes rather ugly - day and night picture of a course of the sun.
Using Task Till Dawn and the workflow described here, you can easily create dynamic background images yourself and use them not only under macOS, but also with Windows!