I did not realise portable monitors were a thing: Best portable monitors in 2023 for laptops, smartphones, or tablets

Laptop with a second screen connected by a cable

To think, I had a second monitor for my laptop at my own office, and one at each of the two clients I spent time at during the week. Once you get used to working with two monitors, it is really difficult going back to a single monitor from a productivity point of view. So, I did not lug monitors around, but three were dedicated for my use when I could have just had one portable one.

These can also be useful as display units for a Raspberry Pi system as well.

Portable monitors are a great way to resolve this problem since they’re more compact and easy to carry around. These smaller displays connect via USB-C and mini HDMI, meaning you can use them with almost any device, from the best gaming laptops to tablets, smartphones, and standard work laptops. Some monitors even come with their own batteries, so you can enjoy consistent productivity and media playback without impacting your laptop’s battery.

See https://www.xda-developers.com/best-portable-monitors/