Electronic keyboards like the Yamaha Motif or Korg M50 often have a "Split" feature, allowing different patches to be assigned to different sections. For example, the bottom 18 or 20 keys can be assigned to a bass patch, leaving the rest of the keys assigned to an electric piano sound. These splits allow not just the patch to change, but the pitches as well. For example the bottom keys can sound an octave lower than they ordinarily would.
Small keyboards often have buttons that shift the octave to the left or right on the fly, effectively increasing the number of keys without the weight.
There is another split type that is possible nowadays but apparently no manufacturer has done it yet. What if the patch or pitch range were assigned to each key in real time by which finger or which hand touched the key?
This would require some type of signalling device on finger or hand that would be instantly recognized by the keyboard. Of course the device would need to be very small and non-interfering with the sense of touch or movements of the fingers. The speed of the sensors involved would have to be quite rapid as well.
What could you do with this? Well, if you are a good pianist, you could play contrapuntal melodies, with each voice in a different instrument.
Or, if you set the keyboard to recognize the left hand as the bass, any key touched by the left hand could sound an octave lower than when touched by the right. Even when the hands crossed, the voices would maintain their separation.
This would make it possible to use much smaller, lighter keyboards to get the full range of notes, or multitimbral setups that ordinarily take multiple manuals could be done with one.