If you are in a position where you can dump random gases into the air supply to the degree it impacts these devices then they are likely compromised in other ways as well.
I don’t know about that. It seemed to have a pretty rapid impact on the phone in that video, and it’s not like those are exactly open. And they weren’t pressurizing it.
Helium is tiny, and will diffuse though pretty much anything other than continuous welded metal pipe very very quickly. The elastomer seals on a phone would slow it down slightly, but the article’s from 2018, before so many phones were watertight. I remember my old iPhone had a little piezo cooling fan in one of the grates on the bottom, so helium would have no trouble at all.
You don’t necessarily need to put it into the air supply, could just bathe the specific device you want disabled in helium from a deodorant can or something
If you are close enough to spray a device you are close enough to just steal it. Or spray the owner.
If it’s bolted to a wall and unattended neither of those things are an option
