There's a bunch of research that suggests you can get a solid productivity boost by adding a second display to your computer although a second display has been limited to the office as displays are usually too big to carry. But USB-C, with its power and data capability is giving rise to portable displays. This means two-screen productivity is now available to travellers and those with limited workspace.
The case for second displays in the office has been diminished somewhat as displays have become larger. Most of the time, I get by with a single 27-inch display and utilise the virtual desktop feature of either Windows 10 or macOS depending on what system I'm using. And, as we've said before, a single display set up can help improve your focus.
One of my former colleagues, James, has picked up a 15.6-inch portable display that connects to his MacBook Pro over USB. He bought his from Scorptec but there are other retailers who sell them. He went for an AOC I1601FWUX which has a street price of around $250. While it only offers 1080p resolution, this is good enough for many applications. And, as well as being handy for use as an extended desktop, it also makes a handy vanity screen for presenters or presentation display for small meetings.
Although it's not a particularly high-spec, and the reviews of the display suggest it's not brilliant, it highlights the ability of USB-C. And for those who need a second display, this looks like a reasonable option.