I've tried using this keyboard on an airplane and it worked well. It fits nicely on a tray and has enough room left for the palms to rest. In terms of focusing on writing and eliminating all distractions this is as minimal as it gets.
One thing I would need to figure out is how to prevent the screen from dimming while I'm caught in deep thought. There is probably a global phone setting that I can toggle. Alternatively I could get a writing specific app that shows larger text and keeps screen on. I'm using default Notes app.
Does anyone have a recommendation for an iPhone App specifically designed for writing?