I can't say that all TVs can playback 4k. Of course there's various encoding methods, containers etc. High bitrates might case problems too. Slow USB drives could even be a weak point.

As I said, I would *expect* any 4k TV with a USB port to be able to playback from a USB drive.

You'll probably find it difficult to get a set combination of codecs, bitrates etc that work on all of them due to the nature of how standard standards end up being.