Couple things, since surveillance organizations like tech companies and government intelligence bureaus have been known for weasel words:

>Speech samples are always analyzed locally on the customer’s phone

OK, and are they ONLY analyzed there? Are they also uploaded anywhere? Are they also analyzed anywhere else?

>automatically deleted after processing

Deleted from where? The local storage? See above, what if it's also uploaded somewhere else?

>nobody, not even the customer, ever hears them.

No human? Are transcriptions created that could be reviewed by a human?