The iPhone Duo has a massive internal screen, but while you would think it's ideal for two-handed use, some may still lament the inability to access everything on the screen with a single thumb. As part of iOS 27.3's developer beta, that's no longer a problem for the iPhone Duo.
As part of the update, Reachability will temporarily shift the left or right side of the screen to the other side with a short swipe. This allows every part of the interface to be accessible from one hand that's also holding the iPhone Duo itself.