So, in the specs for the mini-pc, it claims the video out can do 4K @ 120Hz (even faster if displayport). I assume the 4K @ 60Hz you saw is from the "4K gaming at 60 FPS with FSR" line.

I reckon it can probably stream at 4K@120 if it can game at half that.

Interesting. I also saw HDMI 2.0 - I guess it’s technically possible but with subsampling?