Haven’t seen this mentioned anywhere, and has become much more relevant with iPadOS13.
The portable ZMI PowerPack 20000, which has enough juice to re-charge a 12.9" iPad Pro, has one USB-C port and two USB-A ports.
Uniquely, it ca be put into “USB hub mode” with the USB-C port connected to the iPad. This powers/charges the iPad while also providing a dock/mini-hub function for the two USB-A ports.
I use it to attach a flash drive or XQD card reader to one USB port and a wired mouse to the second port.
Will actually work with any USB-C device (laptops or desktops), but seems particularly useful solution to “dongle town” when traveling but wanting to use flash drives, memory cards, mouse, or other standard USB devices that can now be used with iOS.
The standard USB ports should be USB 2.0 / low power devices, not high speed USB 3.1 external disk drives, but still very useful.