You need to be able to change only shutter speed or ISO, while holding aperture constant. That's not a problem for phones, because they're almost always fixed a

You need to be able to change only shutter speed or ISO, while holding aperture constant. That's not a problem for phones, because they're almost always fixed aperture anyway. And of course any DSLR or mirrorless camera can do it. But some point-and-shoot cameras won't have this capability, they'll want to be fully automatic, not giving the photographer that specific control.