it works, but I don't know if is my device or happen to all MI2S I need to tap/swipe a lot until it turns on.
I have tested it and it only shows a black background , doesn't work with te screen off. If you press power button it turns off the screen. I checked at playstore and yeah it says is only for OLED screens that actually turns off the led when you set a black color.
So this app "work" for our device but actually it eventually drain battery because screen is turned on when use it.