In an AirBnB the kids enjoyed playing with "Alexa" and they know I wouldn't allow an Alexa at home.
You sound like it should be very feasible to have your own, open source home assistant that doesn't arbitrarily phone home?
Discussion
Yeah, iPhone can already transcribe English and Spanish (and maybe other languages) without the internet access, so the technology is there. And with whisper.cpp it’s even open-source and free to use by anyone.
I saw the video in the whisper.cpp repo and yeah, "kill all humans" etc. is understood and prompted out. From there it's easy to trigger some arbitrary actions that play music or IR blast some commands to the AC.