In a first, an American woman used a suicide pod to take her own life. The process took place in Switzerland. It’s done by pumping in only nitrogen gas, so the person will lose goes dizzy, loses consciousness and eventually dies. Enter futurama memes.
This is a different use case, and has different limitations. One of them is portability, another is fit during activity. Neither of these apply to a nitrogen mask for assisted death. In fact, you need a means of gas to escape because CO2 buildup is the cause of discomfort from suffocation, not lack of oxygen. The homebrew device is called a suicide bag and explains in detail why positive pressure, lighter gases, and an opening are preferred.
I’m aware co2 is the driver of asphyxiation and the panic response. The point is the chamber handles that without the need for any fit test or anything of that nature.
If there is a leak of ambient air into the breathing supply of air, the process is not going as expected.
A chamber straight up solves that AND increases comfortability of the subject as they don’t need to wear something on their head in their last moments.
Pretty sure suicide bags don’t have much in the way of fit tests, either, and I mentioned the comfort issue in my very first comment in this chain, no need to revisit it. An air leak into your nitrogen supply is always going to be a problem, possibly a bigger one in the reusable product than the one-off. It only has to work well enough one time.