I have a rule that all my "modifications" must be easily undone, and can't impact the "thing" if it stops working.

So where possible, I shy away from any modifications to the device itself that aren't extremely simple to undo.

A vibration sensor and hall sensor on an esp8266 is cheap, works consistently, and is VERY easy to take off if I don't want it any more.

I did hook into a humidifier once kind of like this, I hooked the esp8266 up to the on-off button, but I try to avoid it if I can.