High Sierra, how to set screensaver as desktop background? explains how to use the Screensaver as an (animated) desktop background. Unfortunately the
-background option to
/S*/L*/F*/S*/R*/ScreenSaverEngine.app/Contents/MacOS/ScreenSaverEngine required to make this work isn't supported any more in Mojave and newer versions of macOS.
So how can a screensaver be used as a desktop background in Mojave and above?