You can run screen savers on your Mac desktop (wallpaper), buy running the "ScreenSaverEngine" with the "-background" option from the command line.

The executable is inside the screen saver application package.

    cd /System/Library/CoreServices/ScreenSaverEngine.app/Contents/MacOS
    ./ScreenSaverEngine -background

(Earlier versions of macOS have the app under /System/Library/Frameworks/ScreenSaver.framework/Resources )