Ditching Wifi makes things very difficult considering that it is increasingly rare to find a device with ethernet, especially low bandwidth devices such as smart homes, etc. Additionally, it should be noted, the KS8000 and those series of TVs have less bandwidth on the ethernet port than on wireless. I know this from previous speed tests with wireless AC on my own KS8000.
To get functionality of the TV’s native OS, you either need the software to be communicate directly with google home, which it doesn’t, or purchase an interpreter, such as a blaster. Everyone will recommend the harmony if you really want that functionality. SimpleControl offers an alexa-enabled, ethernet IR blaster as well.
The only other solution that may work is the NEEO smart home, which seems to have ethernet and an ad-hoc connection between the remote and the brain, likely over a 2.4 GHz link. It may be possible that you could set up the NEEO and never use the remote, and instead, run everything through google voice. I would contact that company to see if that is an option for you.
Naturally, my recommendation would be to use a wifi enabled solution.