Your Google TV will have HDMI audio input to your projector, so you need to connect your projector to a Sonos Soundbar or Amp. The connections you can use are Optical or HDMI ARC/eARC depending on the chosen Sonos product - so if your projector has an optical out, as an example - you should be able to use that.

I would not try to connect to a Sonos speaker using an RCA analog line-out/line-in connection, as you will experience a minimum of a 75ms delay (audio buffer) to the audio stream, causing lip-sync issues with the projected display. There is no such delay with an optical connection, or HDMI audio return channel.

Thanks!  I was hoping to connect over WiFi or Bluetooth to use my Move, Roam, and One.  I also have a port, but that’s in a different location from where we’ll be using the projector.  
 

I may have to upgrade to a soundbar, arc something that can travel with it.  Thanks for your recommendation. 

Oh I’m sorry I thought you were already using a stereo Bluetooth connection from Google TV to a Sonos speaker as you stated you knew about that already. I sometimes do that when out and about in the camper van with a ‘Roam’ or ‘Move’ speaker and a FireTV stick - it’s okay but sometimes the audio may drop (occasionally), or sometimes not be in sync, but it’s okay as a temporary solution when travelling. Probably not something I would choose to use in my Home Theatre TV setup, as I prefer wired surround sound.

Of course it’s a matter for yourself - you could always try Bluetooth stereo to begin with and then consider later moving over to wired surround sound with your Projector and soundbar etc.

Just to also add, the Sonos portable speakers Roam/Move (of any generation), cannot be used as surrounds with a Sonos primary Home Theatre product - so if initially trying a Bluetooth connection to begin with, you might want to consider using the Era 100/300 speakers instead as those can later be used as surrounds with a Soundbar, or Sonos Amp.

We’re thinking along the same lines now!  Good info, thank you.  
 

If I use an Era is it possible to use the line in to then broadcast to the other Sonos products I have connected to the system?  Or would I still need a soundbar or Sonos amp?

You can play the audio over Bluetooth to the Era 100 and then in the Sonos App group it to your other Sonos products on the same WiFi/System to play the audio to those devices too. I’m not sure how reliable that will prove to be, but worth trying, perhaps.

Thank you!