I've installed a few Sonos sound bars/subs, but never paired with rear speakers before.  Reading through the docs I've found that a Connect:Amp can be used to drive rear speakers and that both soundbar and connect need to have wired Ethernet.  Also, for some reason a Sonos Boost is required for this configuration...

My biggest question what comes out of the rear speakers when TV is the audio source?  Is it some type of pseudo surround sound with only surround content coming out of the rear speakers or do you get the equivalent of multi-channel stereo, or can you select between modes?

This is for a bedroom with rear speakers above the bed, so the client is actually more interested in multi-channel stereo type of setup than actual surround sound.