A Dell U2414h 24" - cost 220€ over 10 years ago. It is 1080p, can be detached from the stand with a single button press and fits easily into my Osprey 80l backpack (its more a suitcase than a backpack). For protection I guard the screen-side with a piece of cardboard that is cut to match its size - then make sure to place the screen against the backpack framing and secure it with the straps that are in the backpack.

I travel with a mouse but no keyboard, had to buy one real cheap.