The Newton had an absolutely brilliant user interface, but its hardware let it down. I wish we had a device similar to the smaller Remarkable tablet, running something like NewtonOS.

(Related: Columbo's Mystery Capers is an amazing and hilarious game from one of the Zork devs that has never been dumped and doesn't exist on any other platform. I hope someone will figure out how to get it off an actual Newton and get it to run on Einstein.)