I think it's been fairly clear that people don't limit themselves to OS's that are still supported, and if you remove that condition from your question, I think the answer would be "yes".
I suspect the mention of OSs that are still supported implied they weren't talking about non-supported but no longer supported OSs. So nothing exotic, just the normal OS on the device but stuck at the old version which was the final one released for it.
Hardly. Good luck running non-supported OS’s on iOS devices. So all of the old iphones and ipads are out.
Even on Android only a tiny statistically irrelevant proportion would both with this.