> It also said the microphone was originally included in the Nest Guard for the possibility of adding new security features down the line, like the ability to detect broken glass.

Detecting broken glass with a microphone? Does the device even have enough CPU power (and RAM) to add advanced advanced audio processing features? Or was this going to upload the audio to Google's servers to do the work? If it's the latter, that would necessarily[1] require uploading audio without a wake-word trigger.

Either they just admitted to wanting always on microphones in the home, or they are blatantly ling about why the microphone hardware was included. Designing hardware for a large market usually involves a lot of value engineering to reduce the number of parts or replace a feature that requires expensive parts with a functionally similar design that is cheaper. Saving $0.01 (or less) by removing an optional resistor doesn't sound like a lot, but it adds up if you're selling >100k units. A microphone is much more expensive[2]. A part that costs $0.366 (or more[3]?) needs a good reason to be included, and "for the possibility of new features" isn't good enough. So what was the real intended use that justified including a moderatly expensive part?

[1] The robber about to break your window isn't going to call out "Ok, Google" first so the Nest Guard knows it can upload an audio clip.

[2] https://www.mouser.com/Electromechanical/Audio-Devices/Micro...

[3] $0.366 when buying >10,000. Up to $0.75 in lower quantities. (prices from a random example: https://www.mouser.com/ProductDetail/DB-Unlimited/MO064402-4... )