Right but, did you spot that in your answer you allowed for a situation where there isn't actually that gap of air at all, just because it felt intuitively reasonable to do so?
There is no "air gap" in your sense between say a Sega Megadrive and Google's servers, they're both wired to the electrical grid. But you (not unreasonably) disregard that. In contrast there is technically such a gap between my laptop and Google's servers, because it's running on a battery - however thanks to WiFi it certainly isn't "air-gapped" in the sense we usually mean.
Security Keys are indeed often electrically connected (via a USB port) but the design insulates this from the key management problem so in effect they are air-gapped. Any attack that crosses that gap might equally have worked by shining a laser at it through a window, or holding an electromagnet near it.
There is no "air gap" in your sense between say a Sega Megadrive and Google's servers, they're both wired to the electrical grid. But you (not unreasonably) disregard that. In contrast there is technically such a gap between my laptop and Google's servers, because it's running on a battery - however thanks to WiFi it certainly isn't "air-gapped" in the sense we usually mean.
Security Keys are indeed often electrically connected (via a USB port) but the design insulates this from the key management problem so in effect they are air-gapped. Any attack that crosses that gap might equally have worked by shining a laser at it through a window, or holding an electromagnet near it.