languidicity
I confirm that I have a Honor 400, not Pro. Yes, I've noticed he has the Pro version in the video.

You can check the full specs on a site like this: https://m.gsmarena.com/honor_400_5g-13799.php
It clearly says 1 billion colors. Provided there's no FRC in base model as well as in Pro, it should be a natural 10-bit. I can't confirm it anyways.
PS: I've also noticed that in my country it is MUCH cheaper than Amazon's price.