The best portable monitors I know of (and I have an entire collection of 22-ish full HD monitors in search of the Holy Grail which is a carry on sized full HD monitor as large as possible but they don't make cheap thin 19-20 full HD monitors) are the top half of this shop https://shop57714512.world.taobao.com/ Use Superbuy as your taobao proxy. These are tripod mountable full HD IPS monitors with a CNC machined case and a driver board. Very basic but has all you need. If you prefer aliexpress, https://www.aliexpress.com/item/1920-1080-17-3-inch-IPS-Disp... and https://www.aliexpress.com/item/2ms-15-6-inch-1920x1080-IPS-... and so on seems to be the same thing.
Another solution is https://www.packedpixels.com/ but the size is not so great.
I currently carry a Sharp LL-S201A which is slightly larger than the above ones -- I got a great deal off eBay for once. If I didn't then probably I'd get one of the 17" ones above -- the Sharp needs a VESA mount which makes things unwieldly.