If just looking for a portable display, there are plenty on amazon. I bought a Chinese brand, magedock, because they had a touch screen 1600p model that was more portable than the others (no battery though).
Yeah, Amazon is such a rain-forest though. There's a plethora of devices there, and I don't trust the reviews. I'd prefer a 14", don't require touchscreen (though if it would cost me 50 EUR, I'd go for it, but not double the price like ThinkVision M14t). Speaking of which I've seen the ThinkVision M14 for 180 EUR, that's a fair price. It has high brightness of 300 nits (better than the Asus one, of which the 16" gets recommended a lot even though its barely readable in sunlight), though reportedly also has coil whine. However, it _only_ supports USB-C. So I would need some kind of adapter I guess. A lot of the Chinese stuff has the adapters included, but even the brandnames just don't make sense. Magedok was out of stock (they didn't have Magedock). Battery I don't care for; I'd just hang a powerbank behind it with velcro.
