It probably doesn’t matter because the swipe-up gesture works on the entire bottom of the iPhone screen, not just in the middle.
So you’ll be going ahead with a centred FAB? Irrespective of:
I don’t know yet, but I don’t rule a centered FAB out – mostly because it solves the problem of left vs right handedness.
Alternatively, if that doesn’t work out for you folks; you could totally have something like ‘Pull to Reach’ from a music player, Soor. I’m not sure how it’ll work with this Contexts menu that has been teased; but maybe one pull to select the said menu and another pull to navigate through it?
[Video sourced from Soor’s Press Kit, so legal to share here]