I know there are applications that allow you to do videos through applications, for instance USB Camera - Connect EasyCap or USB WebCam, but it does not allow you to use the USB camera in Streaming applications such as Google Meet.
It is known since 2017 that standard Android API does not support them: the thread How to open usb camera in android using android.hardware.camera.external's answer:
There's currently (as of Android O) no common USB camera support on Android devices via the standard camera API.
Some Android manufacturers do have their own support for USB cameras, but it's hard to know what devices do and what don't.
So I think the only way to have USB camera in all streaming applications is to have driver support for USB cameras in Android. I need the feature because of Corona pandemia, and have a need to stream while driving etc, and there is no phone that can have sufficient streaming video quality.
I know the project External USB Cameras, but it seams that you need to root your phone to do it, which I have not done.
I have not seen any attempt for the implementation of USB cameras in Linux kernel. I think the Linux should first have the support before android API will get it. Debian's Webcam article here, Package libv4l-0.
Phone: OnePlus 6T.
Android: 10, newest.
USB camera: Logitech C922 Pro HD Stream Webcam.