Use Two Amps as Surround Speakers with TV as Center Channel

No. Sonos has no option to allow an outside system to provide the center channel.

Im not aware of any system that would allow what you want to do. 

The center channel is provided by the TV via standard speaker wire inputs, just like a normal center channel.  My question is more directed at the use of two AMPs. One to power the rear and one to power the front.

No, the front Amp would connect via HDMI-ARC or optical, and get the full 5.1 signal, not just front right and front left. It would then create a phantom center channel from the front two speakers, and send the LFE to a bonded Sonos SUB and the surround channels to the bonded Amp driving the rears. Sonos does not provide any way of ‘splitting’ or ‘suppressing’ any of these signals.

This would be a nightmare in the marketplace.

First, I don’t think that any existing TV would accept a speaker level input from an external amplifier.

Second, speakers across the front should have similar timber, else an actor’s voice will change as he or she walks across the stage. And, TV speakers are traditionally very limited.

Next, the TV would need to strip out the center channel and send the remainder to the external surround processor. I doubt that this would make any sense to a TV designer and it would create support issues as users misconfigured the TV.

Finally, changing Volume would be a mess because both the TV and the external system would need to track the change.

This would be somewhat easier to design and configure if the TV did not offer any Apps, but such a TV would be nearly dead in the current marketplace.

Next time Best Buy allows people in the store check out this Sony TV A9G with center speaker option (read the manual for inputs).  It is an awesome TV all around and works great with a standard Sony Receiver hook to in-ceiling speakers when it is in its dedicated center speaker mode.

https://www.sony.com/electronics/televisions/xbr-a9g-series

What I don’t like is how a Sonos Connect works though a standard amp. Like many posts the volume is difficult to get right and a standard receiver draws a lot of power to just be playing music all day.  

I forgot about that SONY model. The center channel feature is not mainstream.

I’d assume that the Sony TV is only compatible with home theater speakers or AV-receivers made by Sony.

Why would you assume that?  OP already stated that this is not the case...

No, he did not. He stated …

The center channel is provided by the TV via standard speaker wire inputs, just like a normal center channel.

Have you ever seen a HT setup composed of modules from various vendors?

Yes, that is the way this TV can be configured (per the link the OP provided)…  No mention of a Sony product feeding the speaker wire inputs...