I picked up one of the ARZOPA ones and they are fine. Not the best looking, but good enough for a second monitor on the go. I used to take my ipad 9.7" with me places for this purpose and even though the image isnt as good, its way less effort to carry around.

I wouldnt use it as a single monitor regularly, nor for gaming.

I had to keep using the usb-c cable that came with it. Not sure if its a specific protocol that my thunderbolt 4 cables dont support or not. Minor inconvenience i havent looked into further.