Just change your wallpaper folder in settings to [OneDrive]/Pictures/Wallpapers and it will change periodically.

This Trigger fires every time a new photo is added to the Editors' Choice page

This Action will download a file at a given URL and add it to OneDrive at the path you specify. NOTE: 30 MB file size limit.

Set Landscapes Editors' Choice photo on 500px as your wallpaper