Another tip:
If you’re going to use a lot of these devices, you can simplify their identification within the Alexa app by giving them unique names in the Arduino code. I used “SonOfWemo” in the examples above, but you can change that to any names you like.
SonOfWemo was just a little pun, alluding to the fact that the device was the “offspring” of the Belkin Wemo, and built on Sonoff hardware.