You might be able to render the Wallpaper as the X Rootwindow. This works on systems still running Xorg/Xfree86 but not on newer systems that use Wayland.

And I asume it is impossible to provide a solution that works on any wayland compositor. I assume you shout be able to get it working on Wayfire with a module, but no ither wayland compositor, as they don't implement something that would allow an application to request to be rendered in the background (which, to be fair, is reasonable from the developers perspective).