The 1-Click flashlight works! It is truly one click. You open the app and it shows a white screen that can be used to (dimly) illuminate your work area. You have the option to choose a different color, though I don’t know why you would. The app also has a strobe functionality (in case you wanted to give someone seizures), which flashes the screen on and off.
The app makes it simple to increase the brightness of your display with a slider, which is nice because the default display (and where I keep my iPod) is not the highest brightness, therefore, the app doesn’t do its job unless you drag the slider to the full brightness setting. Unfortunately, I don’t think Apple iOS lets the app automatically set the brightness level of the device and turn it back down when the app is exited, but manually setting the brightness is not too much trouble.