I ran into this trying to get a smart thermostat. Nest is problematic right off the bat because Google, and their main competitor Ecobee comes with an onboard mic + alexa. Luckily I found an engineer who posted a comment/review mentioning the alexa mic can be unhooked inside the phillips-screw-accessible rear housing in <30 seconds... so that made it an instant buy. The idea of an always-listing wifi thermostat in my house is incredibly creepy.

This happened again with the LG CX, surprise! It has a mic for alexa too! Luckily it's only on the remote. Guess which little dot is getting a tiny bead of epoxy first thing?