A german magazine just made a video on that topic. You can activate english subtitles. https://www.youtube.com/watch?v=hBSEHpU-pyI
They tested a bunch of smart tvs and tv-sticks and their network activites.
They say that roku devices were the most privacy friendly tv-sticks.
And if you dont care about warranty voiding, open the tv and tape the things you dont want. Mic, cam, etc. Its probably the cheapest option