[ajdude]

Are there any 4K digital signage screens as high-quality as some of these OLED smart TVs?

[MBCook]

OLED would burn in, I doubt you could find that.

But can you get 120hz? Or VRR? Low latency? Any other good feature?

I doubt it. I suspect (as it seems you do) that if you want anything past a bog-standard tv you’re out of luck.