If you ask this community, i expect thickness of the device not to be the show stopper.
Just look at the pyra or pd pocket.
Battery life however is at least my concern.
Adding a Kbd to the device will make me use it more often than the manufacturer calculated "get through the day" with one battery load activity pattern.
Any additional 1000-2000mAH would be greatly appreciated to not become a wall or powerbank hugger.