Was just looking for this, apparently Sceptre makes some. I had never heard of them.

Best Buy also has a filter for 'non-smart'. Tho the results don't seem very good, at least a couple had reviews calling out that they had smart features.

But yeah, by default I think the main option is to not connect a smart TV to the Internet. But then you have to do research to make sure it allows that, and doesn't try to rogue connect to open networks.