The absolute bare minimum for DUET to function is complete; technically, the hardware could be feature complete like this, with everything else being for the sake of pizzazz. I’m debating basing DUET around the Magic Keyboard, and making the Pi and add-ons more like a backpack that straps onto it, primarily for the sake of being able to use the keyboard on the iPad directly from boot; but I’ll probably use a real keyboard and enclosure, again—for flair.