A free app for Android, by Nine Nines.

Transparent Screen & Live Wallpaper is a handy utility that lets you apply live wallpaper to your mobile phone screen. It will allow you to see the background behind your device’s display.

You can choose to use the back or from of the camera for your desired live wallpaper. 

You can change the wallpaper on your phone screen with one tap. All you need to do is install the app and follow the on-screen instructions.

It is a completely free app. There are no hidden costs, no extra fees, and no in-app purchases.