No. A 15-year old (so not ancient) dumb microwave.
Not a luddite but, aside from a couple of Alexas, just no need for any IoT.
How did you start a fire with a microwave? Plain old electrical fire, rats eating wire insulation?
Apparently a short circuit in the control panel in the middle of the night. At least that's what the investigator said. I wasn't using it and was asleep. So I didn't start it. Was spontaneous. Didn't seem to be related to any external wiring.
We had a dishwasher let out the smoke recently. No fire, luckily, just literal smoke and melted plastic. The melted part was the mechanical power switch. Yes, dead simple non-IOT holy century old technology. The parts that fail are almost always the moving parts and almost never the smarts.
My washing machine was intermittently staining stuff for a while. The it started smoking one day. Should have replaced it at least a couple years prior. Bet it was a good 50 years old.