I have one; I opted for a rather cheap option, however, so its usefulness is somewhat limited.
But even considering that, it's a nice and simple way to extend screen real estate, and it *was* a real asset during the pandemic, enabling me to have multiple applications visible when working (teaching) from home, whether I was at my desk - or somewhere else in my flat. Which would correspond to travel needs, no question about it. Imagine *two* 14" monitors instead of one for a laptop computer, with the second screen adding much less than the weight of another machine to the whole package. Even my own travel tablet
I'd opt for a well-featured one, though - a good touchscreen with active pen functionality included (mine doesn't offer touch at all), and a good colour gamut; mine's frugal, though the panel *is* better than on many affordable laptops which is quite a feat at the price; I paid about a quarter of the price of the cheap-ish laptop I was using at the time (an Acer Swift 1 from 2018, Intel N5000 ... *really* frugal). Check if your laptop can actually power and drive the screen - correct USB 3 specifications are mandatory; it's best to have a fully decked-out USB C port and a machine from 2017 or later; the key's DP Alt mode and the availability of a suitable driver (the latter's a given - but you need to download it).
M.