Earlier quoted context omitted.
Eh, I think you're being uncharitable. My 80 year old mother could definitely figure out how to hold down a button while turning the thing off and on. We've been living with some version of that reality for decades.
Also to set up a wifi network with a particular SSID and a device on that that runs a TFTP server?
Just have support walk them through a menu on their phone for an "advanced" feature they just tap on, then hold the button on the microwave. Voila!
(Granted, I did tech support long enough to know this isn't easy; if someone can follow instructions, however, it should be doable.)