Many details in here about nuts-and-bolts operations of digital assistants, companies and contractors that process the data, and legal frameworks surrounding their use.
Unfortuanately, much of content is explanation of what is possible vs actual privacy violation cases which have occurred (you may find them in the footnotes which I didn’t have time to fully read). They do cover specific cases of contractors reviewing conversation recorded by assistants and being able to identify the speaker.
It might be a good reference to have in your back pocket if you ever need to have a debate with others about smart assistants and the attention paid to “The Role of Consent and Reasonable Expectations of Privacy” is particularly relevant as the notion of contact sharing without consent becomes a larger part of the collective consciousness (e.g. Clubhouse invites, etc).