You can’t do all of that with a single amp.  The amp is only capable of 2 audio channels.  In order to get 4 channels you’re looking for (with a simulated center channel) you would have one amp in front and one for the back surrounds that is wirelessly ‘bonded’ to the front amp to form a single Sonos room.

Regarding the outdoor speakers, Sonos amps don’t have A/B switch built into them to switch between 2 sets of speakers.  You can connect to pairs (identical speaker channels) to a single amp. but they would be playing the same audio at the same volume, always.  To get around that you would need a 3rd amp just for outdoors, or since you won’t play outdoors and inside at the same time, a stand alone speaker switch to go with that front amp.

Sonos can fit your needs, but honestly, considering your specific need for 3 pairs of passive speakers, you might be better off with a more traditional receiver.  There are 7.1 receivers where two channels can be dedicated to a 2nd zone (your outdoors), so all your speakers are controlled by one device.  If you want to use Sonos for streaming content, then you can add a Port to that setup.

Danny - Thank you very much for the thoughtful reply. I’ve been trying to figure out a way to go with the amp but you’re probably right, a standard receiver will likely best serve our needs. I wish there was a product on the market that had the ease of use factor that Sonos offers. I just haven’t landed on it yet.