If you would spend $20 more on a dumb device, spend that on a wifi router just for the TV - plug an ethernet cable into the TV's port, feed the credentials of a

If you would spend $20 more on a dumb device, spend that on a wifi router just for the TV - plug an ethernet cable into the TV's port, feed the credentials of a new network to the TV, whatever -- and don't connect that to the Internet. Put a label on it. Now you have a smart TV which can whine all it wants, but can't phone home.