Typewise Offline is an Android keyboard with two departures from the standard. The key layout is hexagonal rather than rectangular, which the developer states makes keys substantially larger for the same screen area, and common editing operations are gestures rather than keys.
The layout argument is that a rectangular grid wastes space between keys and a hexagonal arrangement packs the same number into the same area with more surface per key, which reduces mistakes made by hitting the boundary between two. Gestures replace the keys that consume space without carrying letters, so swiping up capitalises, swiping left deletes, and swiping right restores what was deleted, which removes several dedicated keys from the layout entirely. The property that matters most is not the layout though, it is that the keyboard operates entirely offline and does not request network access. That is worth more than it first appears, because a keyboard sees every character typed on the device, including passwords, messages, and authentication codes, and it is the single most sensitive component a user installs. Prediction and correction running locally rather than against a service means there is no path by which typing leaves the device, which is a structural guarantee rather than a policy commitment.
The layout takes real adjustment and typing speed drops before it recovers, which is a genuine cost and not everyone gets past it. Anyone unwilling to spend a week being slower should not start.
Link: Typewise on Google Play