But I have no idea where you live, so that might not be a good option for you.
A bit south of Sweden. There are several online shop still indicating they have them in stock, but after contacting by phone they all say they ran out. If you can wait for shipment from China that may work. eventually. Using phones as USB webcam is a mess, require android debug systems, phones overheating, wrong sound source, 2 second latency, etc.
One of the largest retailers here (big enough to keep Amazon out of this country):
https://www.coolblue.nl/en/webcams except for the 2 most expensive, that whole page is "temporary sold out"
Not sure about the application you will need the USB webcam for, your DIY skills and free time, but you can harvest a webcam module from an old/defective notebook you have in your pile of old electronics or aquire locally (this might give an idea how:
). Audio would be a second topic, depending on the given hardware.