You don’t suffocate with nitrogen, I’m not certain on the specific scientific terminology but nitrogen is an inert gas; meaning your body/lungs don’t react to it like CO2, you just die.
That doesn't happen. The gasping reflex is triggered by excess CO2 build-up in the lungs, which never occurs with this method. CO2 gets exhaled normally, but what you inhale has no oxygen. You just quietly pass out, and in about ten minutes you're gone.
As far a I'm concerned, I want one. I'm not ready yet, but at 77 I'm becoming aware of the endless horror of being warehoused in a "care facility", as is already happening to some of my contemporaries. I spent a week last year in one recovering from surgery, and that was more than enough.