Typically it is not possible to convert any image file type directly to APK. However, some apps can use images or even videos to create rich and sometimes animated wallpapers for Android, which is what wmv to apk conversion might refer to. These are generated as APKs, i.e. programs that are installed and run in the device to replace the wallpaper.
Which means that this is not really a conversion per se, more of generating a simple Android app that contains the image your video you import in to.Open WMV file Open APK file
An Android wallpaper design app