Maybe this only works on screens 5.7+ inch devices, as of now. Holding the windows button shows the one handed mode which also works on my device (Lumia 535). I think as of now, the moving keyboard feature only works on the Lumia 1520.
It works on the lumia 640xl
Like what I have said, it might only work on screens 5.7+ inch devices, as of now.
Yep, i think only supported on 5 inch screen's and larger.