I've never used it as a DMD, but this is a great small monitor:

https://www.amazon.com/ELECROW-Raspberry-1920X1080p-Touchscreen-Capacitive/dp/B082HWF2HW/

The Unit is 6.5" high and 10.5" wide - the screen is slightly smaller than that.

Connect with HDMI, I use mine as a small arcade monitor.