Your Little Timmy will be devious...
You won't just find Doom running on the thermostat, you'll wind up with the frig, the toaster, the microwave, & the lights all running CryptoMiners, talking/plotting amongst themselves on the best way to slaughter all those pesky Humans, & the cat refusing to come down off the tallest object in the home because the Roomba has now been "upgraded" with a Hunter/Killer functionality that makes it especially hostile to any/everything that sheds on its nice & clean floors.
Don't even get me started on what he's accomplished with the unholy union of the car's infotainment system, your SmartTV, & the IOT-augmented toilet...
=-)P
My own Little Timmy has already graduated to getting his creations banned by the United Nations as Weapons of Mass Distraction... I'm so proud! XD