(Yes, I do understand that "privacy" here is mostly about not sending it for processing to third parties.)
Then why does it puzzle you?
Perhaps your definition of "private" is more stringent than most people's. Collective privacy exists, for example "The family would appreciate some privacy as they grieve". It is correct to term something "private" when it is shared with your entire household, but no one else.
- handles it locally, if you have fast enough computer
- sends it to home assistant cloud, if you set it up
- sends it to chatgpt, claude sonnet etc. if you set it up
The main pitch of a tool like this is that I can absolutely verify it's not true.
I'm currently running a slightly different take of this (Esp 32 based devices, with whisper through Willow inference server, with Willow autocorrect, tied into home assistant).
For context, it works completely offline. My modem can literally be unplugged and I can control my smart devices just fine, with my voice. Entirely on my local network, with a couple of cheap devices and a ten year old gaming PC as the server.
My data
You can test this in a couple ways: they'll respond to their wake word when the internet is down (but have an error response). You can also look at the outbound data and see they're not sending continuous traffic.
Not to say with the proprietary products that they couldn't sneakily change this on the fly and record everything, maybe even turning it on for a specific device or account.