Conversely there are USB-C hubs that allow video out and up to 4 usb devices to connect to a single cell phone. I have this one - Hootoo Hub, which even has an SD card reader than my cell phone can pull pictures and files from.
So the android OS automatically picks up USB mice+keyboards? How does the android OS know what to do w/video output over USB 3.0 OTG as far as detecting a panel and its characteristics (resolution, refresh rate) over a USB 3.0 to HDMI adapter? I notice they do have USB panels now, but how would you get the drivers for them on a smartphone?