Comment by ants_everywhere

I assume here you're referring to the user?

It seems like users can have iphone listen to audio keywords, but I don't use Apple so I don't know the details. https://support.apple.com/guide/iphone/use-vocal-shortcuts-i...

Obviously an experimental advertising system would require a special deal with the phone manufacturer and would be covered by Apple's very broad license to advertise based on your data.

That doesn't mean they're doing it, of course. I'm just not aware of technical or legal barriers.