Does iOS 13 (aka, iPadOS) provide better support for connecting a webcam to an iPad? Does iOS 13 (aka, iPadOS) provide better support for connecting a webcam to an iPad?

If it did, then an iPad would become an excellent device for supporting video conferencing, since using its USB-C connection you could then connect it to an in-room speakerphone, videocamera, ethernet, and power, and use the iPad's screen for displaying remote participants.

My understanding is that the only thing that stops this from working right now is that in iOS 12 the iPad does not natively support connecting to video cameras.
There has been no mention of enabling video or audio streaming over the usb-c connector. The two features they are adding is to allow your iPad as a monitor for your mac, and now you can use a thumb drive or external drive via a usb-c and access the files via the file browser on iPadOS.

"Connect an external hard drive, SD card reader, and, yes, even a USB drive." https://www.apple.com/ipados/ipados-preview/

You might be able to wire something up via homeKit. But you'd need to be doing wireless, and there may even be wireless solutions to this day. But they are no adding anything new for native wired audio/video over usb-c.