The 75ms delay will affect lip sync, but if that’s really what you want to do then just plug in a suitable cable and use the app to set it to Line-In. I also recommend enabling Auto-Play.

And I’d also want to be careful about the ‘volume’ associated with such a cable. Sonos is looking for a ‘line level’ input, something variable can cause issues. If forced into a variable output from the TV, I’d set it for 50%, at least for setup. Once it’s working, you could adjust both the TV’s output level, and the Sonos’ input levels to get to a point you want to accept.