For now, I've settled for buying a smart TV and not connecting it to the Internet. Until they come up with a way to phone home without my Wi-Fi, I think I should be safe from spying and vulnerabilities..
There's no presumption, this is known.
https://www.businessinsider.com/smart-tv-data-collection-adv...
I've seen several reports that some TVs will find and connect to an open Wi-Fi if you don't set them up, and then phone home that way.
Probably better to connect it to your Wi-Fi, but block its access to WAN. Or open the TV and remove the module entirely.
I'd also argue that the built-in apps on "smart" TVs increase the manufacturer's profit margins rather than reduce costs for consumers. Sure there are some brands/models that compete on affordability, but others don't need to. After all, did the price of the iPhone go down as Apple scaled up and reduced the cost of manufacturing? No. They just started making more money off of it.
At the same time, folks all over the internet like to mention finding dumb TVs but never provide links, model names, or even just brand names. Why? I've looked pretty hard and can't find any actual verified dumb TVs that are actually for sale anywhere. The top comment in this post at the time of this writing directly mentions finding a buying a smart TV, but provides no further details.
For the one smart tv I do have, I just don't have it connected to the internet. Even then, I have no way of knowing if it's connecting to any open wifi networks near me.
https://www.samsung.com/us/business/products/displays/ under "4K UHD Displays"