(I’ve moved this to projects so you can get individualized responses based on your own needs.)
You should definitely be able to rig some kind of contact sensor as long as the stove as a whole doesn’t get too hot. People use these on turn bolts on doors and on washing machines. They look pretty clunky, and I wouldn’t bet my life on them, but as a convenience notification it might be useful.
Here are some examples:
The aeotec triangular door sensor would be worth looking at as it is smaller and flatter than the box sensors.
As far as monitoring the room, there are a number of VOC monitors now with IFTTT channels, so you could get indirect integration with SmartThings that way. Foobot, Netatmo, oneHug and Awair all have IFTTT channel/services. There’s a beta direct integration with Netatmo, but check the forums – – people have reported a lot of problems with it.
Again, I wouldn’t bet my life on them, but as a secondary notification they could be useful.