Unfortunately, this is not possible. 

On top of @Airgetlam’s answer….let’s add that Sonos pays a licensing fee to Amazon and not the other way around. 

Didn’t want to get into the blame game, but as far as I’m aware, this is a choice by both Amazon and Google, not to allow third party (read: Sonos) speakers to synchronize with their own hardware. My suspicious nature suggests that this is an effort to maintain the sales of their own hardware, at the expense of users who have multiple manufacturer’s devices. But I could be wrong there, and it’s also possible that it’s just an issues with the push/pull nature of the two devices, operating in very different “worlds”. 

I think Amazon, not sure on Google, allows 3rd party hardware to sync, but that hardware has to be single devices that only work with Amazon’s multiroom streaming platform, not part of a separate platfform the way Sonos is.   I’m not saying that Sonos would definitely be on board if Amazon allowed it, but Sonos does work with airplay.

I think it appears that all multiroom audio is the same, and speakers from different brands should just work together with little effort.  It’s just not the simple though, and Amazon and Sonos multiroom audio have quite a few differences that would be quite challenging to properly integrate.

Thank you all for your input.

Thought the status quo would be an ongoing thing.

I have 5 Sonos speakers and 3 Amazon Alexa echo products.  For 2 of my echo products, when I tell Alexa to play, it plays on my outdoor Sonos products instead of the Echo speaker.  First, why is this happening as in both cases it just started one day without any particular intentional entry on my part, and second, how do I fix this?  Thanks!

Look at the Alexa groups in the Alexa app and you will be able to see why this is happening. 

I am in the market to figure out the best set up for my current 16 speaker while house Sonos system. I have 4, Play 3s and 12, play 1s and a boost. 2, play 3s  are paired in family room and 2, play ones in my living room. The other 12 speakers sit in their own room (4 bedrooms, 3 bathrooms, kitchen, game room, laundry room, dining/piano room, garage). My system works well except when I want to play all at once I get a delay getting them all up to speed and  when I rewind or skip they cut out. I have my Boost hardwired into my Ethernet switch but that has not helped a ton. Anyway the reason I am reaching out is I just learned that I can get an echo product to talk to to help run without changing out 14 of  my speakers.   Do I get an echo dot for each room?  being that all reviews say the Sonos speakers are   superior to the dot speakers can I set it up that  the dot does all things Alexa but doesn’t play the music only the sonos speaker does?

Yes, a Dot can be used for Alexa voice functions and automatically route the music to a Sonos speaker.