To be fair, most TVs on the market are buying panels from the same few manufacturers. For example, Hisense sources panels from part of LG. I think Samsung is another manufacturer.
So a new company could theoretically access these panels to make a privacy friendly TV without as much capital.
But like you say, it wouldn’t be able to compete on price, because the ad tech lets other companies sell at a loss.
And they still do it anyway because why wouldn't they? My $4K+ TV still wants all sorts of "personalized viewing experience" access.