This fully adjustable monitor mount is great value and cheapest it has been in a while. It's more of a set and forget type of monitor stand, so if you need constant adjustability you might want to consider a gas spring mount stand instead. I prefer this style though as I've had issues with the cheaper gas spring stands sagging/getting weaker or needing constant readjustment over time.
Details:
Pole Height: 17"
Arm Length: 18"
Weight Capacity: 22 lbs
Articulation: -90° to +90° tilt, 360° swivel, and 360° rotation
VESA Standard: VESA 75x75mm and 100x100mm mounting holes
C-clamp: Maximum desk thickness of 3.5"
Screen Placement: Portrait or landscape orientation
Cable management options
I got this, holds up an aoc 34" fine so Xiaomi 34" should be fine too.