(2019-06-10) Tap Wearable Keyboard

The Tap wearable chording keyboard looks interesting, esp for use with a phone (and earbud).

Mar'2018 review is rather critical.

Nov'2018: you definitely need good hand/finger dexterity to use this keyboard and you need a flat surface to tap on. Although you can tap in the air, the accuracy suffers a LOT.