There are still some dumb TVs in the very low price segment, with questionable panels of course, or im the signage segment, very expensive, of course.

I recently bought a 2018 Samsung TV that I fully expected to use with some extra device, but it turns out the software isn't even that obnoxious (closest thing to an unremovable ad is the linear TV guide in the source selection). It has YouTube, Netflix (which can't play 4K on Linux), and can play modern formats reliably and quickly through DLNA/UpnP.

I do have my concerns about its security - maybe it's already part of a bot net. Feature updates are out of the question anyway, so let's see when I'll have to get a secondary device.

I don't know the others, but the Tizen platform seems relatively light weight. While other systems (Android in particular it seems) can take a long time to cold boot this one only needs a couple of seconds.