I don't know about Gura, but that's Ironmouse's real voice. It's like that because of a lung infection caused by her immune disorder. https://en.wikipedia.org/wiki/Ironmouse#Career
Very cool how someone in her condition can interact with the world via an avatar.
Soprano is very high pitched, so she would have had said high pitched voice before hand. The pitch of a voice is not super related to lung capacity, so much as mouth/vocal chord/throat shape
I’ve heard statistics that most women are sopranos. It’s just that most don’t have voice training.
Likewise… and this may surprise you… I’ve heard statistics that most men are probably tenors. Like, 80%.