Hi. The Port is designed for stereo audio only and this would be a major cost, only to produce something significantly inferior for TV sound than Sonos' products that are designed for TV.

You have every right to request this, but it is never going to happen. 

What would the Port do with the home theatre audio once it’s received it?  It would need to pass that audio data on to a 3rd party amp somehow.  Wouldn’t that defeat the point, since your amp could just consume the audio directly?

If your motivation for this is more control related, so that all audio goes through the Port, and you never need to switch inputs on your amp….that wouldn’t work as well as you think.  Most receivers/amps have several inputs.  The port currently has one, with an HDMI-ARC being a second input.  If you have a TV and 2 sources...your plan won’t work.

Also, Sonos has a ‘Works with Sonos’ program with Onkyo/Pioneer receivers setup so that the Port can turn on your receiver, and switch it to the right input automatically.  Not full control of the receiver through the Sonos app, but perhaps a step towards what you’re looking for?  I have not tried it out myself, so can’t speak to how well it works.