Does Mapillary work on iPhone Duo?

Not yet. Mapillary runs letterboxed on the inner display, with black borders around an iPhone-sized window. Owners report it runs letterboxed on the inner display.

Is Mapillary letterboxed on iPhone Duo?

Apps built with the iOS 26 SDK or earlier show black borders around an iPhone-sized window on the inner display; iOS 27 apps resize to fill most of it, and iOS 27.1 apps fill it completely. Current status: Letterboxed.