There are a couple of references to supported devices that include the ESP8266. But when you watch the video at https://www.arduino.cc/en/IoT/HomePage, it gives me the idea that there are only specific named Arduino devices that can be connected. Any help on this would be appreciated. Thanks.
Oops, just found the answer at the bottom of this page: https://www.arduino.cc/en/Create/FAQ#toc13 "Nope." So there is some conflicting info as this new capability comes up to speed.
And now I find, under 3rd party boards on https://create.arduino.cc/devices/, the following interesting sentence "If you’ve set up an ESP8266 board you can attach it to a thing and set up a dashboard in Arduino IoT Cloud."
Turns out you can have one 8266 device if you have a paid plan at the "Maker" level.