Awesome post. Other considerations can be use of a device with auditory prompting features (consistent throughout the device), a device that can be fitted with a key guard (for tactile differentiation/distinction of keys/buttons/messages), and use of other tools such as tactile stickers or wiki stix around key guard square/s to help orient the child to the device (e.g. "go home button," corners of the device, middle of the device, "clear" button etc.)
K. Reynolds - 6/8/2017