In the context of nomadic living, USB outlets are commonly used to charge devices and run small electronics like personal fans. They are frequently installed as part of a built-in electrical system in a van to provide convenient power. USB outlets are included on nearly all portable power stations, and are installed in many vehicles in addition to auxiliary power ports.
USB is 5v, unlike the house power system which is typically 12v. Since the voltage is down-converted for use, USB voltage can remain stable while the van's electrical system voltage fluctuates. The lower voltage means extension cords or long wiring runs may not work well.
Most USB outlets provide .5A (2.5W), 1A (5W), or 2.1A (10.5W).
USB-C, battery charging mode, etc., can be higher.
USB cord management
One strategy to reduce the number of cords and chargers you have: replace all your cords with new magnetic USB cords. They come with different size magnetic tips (USB-C, Micro-USB, Lighting, etc.) that stay in your devices' charging ports all the time, and you can connect them to the magnetic table. That way, all of your devices can use all of your cords, and they're quick disconnect. Make sure you get ones with higher Amp ratings (5A) for faster charging. Another advantage is that your devices' ports are always occupied by the magnetic tip, so they're less likely to get dirt and water inside them, and they'll last longer since you aren't always plugging/unplugging.