I bought that exact gun safe from Amazon more than two years ago. It has worked perfectly for me. I trained my thumb and index finger, of both hands, in several positions. It takes about three seconds for the safe to open. My wife, son and daughter can also open it with their index finger.
Dirty and/or very dry or cold fingers sometimes fail, especially if dirt or finger oils smear the window.
After about a year the batteries weaken and the safe beeps every 30 seconds, letting you know it's time to change. You have about 30 seconds to change the battery without losing the training.
It also comes with hardware to allow bolting it to a stud or shelf.
It contains my ammo and some other gear, but not my weapons. They are in a more convenient location always with me