You don’t need a stand, you could also use a salt and pepper shaker, a wedge of plasticine, your girlfriend/boyfriend’s knees...
Sheesh, try to be less pedantically rigid, honestly .. it’s a cool app idea. All it takes is for the user to mount their phone vertically while they’re using it.
My original comment was perfectly reasonable…
Sorry if asking clarifying questions about your hypothetical app seems to have hit a nerve.
The misunderstanding is, yes, for this app you would need the phone to stand vertically, so yeah, some kind of mounting adapter would be needed, or at least the user has to find a way to expose both cameras on the horizontal plane while also having their hands free ..
It would be a pretty cool app, but yeah there is the requirement that the user mount their phone somehow. My thoughts went immediately to 3D printing a little holder, but yeah, even a bit of ducttape would do it. ;P