I believe that Eugene CAT is using the Nuvinci hubs on their pedal assist cargo bikes with good luck so far. They've torn up other drive configurations.

It is a Continuously variable transmission (not automatic), because it would be manually activated.

There are "autoshift" drivetrains for bikes, but I haven't heard of them also being used with power assist. A couple of companies have also been working on Autoshift for Di2, again not EV specific.