I have downloaded 10.2 and configured my Sonos system for Google Assistant. I have 4 Sonos Amps and 5 Sonos Beams+Ones+SUBs. I have 9 Home Hubs and 6 Minis.
Some early observations for which I would appreciate feedback/confirmation from Sonos Support:
* Only rooms that have a Sonos Beam or Ones can be directly paired with Google Assistant. My Sonos Amps do not appear to be controlled by GA (e.g. using a Home Hub or Mini as a "microphone" for a Sonos Amp).
* Related, none of my Sonos speakers appear as targets within Google Home to which you could map "default speaker". For example, map a Home Hub to a Sonos room as the default speaker.
* I have configured Google Music (for which I have a premium subscription) as the default service. But every time I ask Google to "Play [artist or song]", the Sonos responds saying "I can't do that here but you can ask me to play it on one of your other devices."
* In Google Home, there is a Sonos TV Control for each Sonos room including the Amps. This must be manually adopted to my home, then assigned a room in the Google Home app. However, it's not clear to me what the TV control does given that it isn't a speaker (e.g. perhaps permit voice control of the Sonos Beam/Amp's HDMI-CEC via Google Assistant?).
* It appears that you cannot cast to a Sonos system (e.g. open YouTube and select Cast or use similar control on Android phone). This may be why I cannot map my Sonos rooms as "default speakers"