Earlier quoted context omitted.
Wouldn't it be great if a universal standard existed for devices sending their diagnosis via audio? If there is a microcontroller and a beeper in there anyway, at only the extra cost of internal memory? Instead of a modem-type modulation and a speaker, make use of the bare minimum piezo beepers and send something that is universally understood? All of that without FCC, no extra hardware cost, no backchannel und thus…
An appliance could just have blutooth so it can connect to an app on your phone. With the machine not having a direct internet connection, the app can collect diagnostics, metrics and do software updates. Require you to press a button in the machine to pair it to your phone. 99% of the functionality with 0 annoyance and ~0 security/privacy risks.
Kinda of like a bluetooth X-terminal, but way way simpler. Think tkinter over bluetooth, probably sans canvas.
A bunch of people will say to just use wifi, make the device a Hotspot, and use your web browser. That's not a bad idea, but tiny devices aren't going to run web servers dishing out multi megabits frameworks.