So you are looking for a thin, compact keyboard for your smart devices? The Wekey Pocket might be just what you need. This is a portable keyboard that is 0.24in thin when folded. It is slim enough to fit in your pocket. The device supports smartphones and tablets.
Wekey Pocket has a foldable, bendable PCB. It has a battery that lasts for months without recharging. This is a water resistant keyboard. More info is available here.