You can use a Black Magic Design Web Presenter which allows connecting 2 pro camera/lens setups via HDMI/SDI, and XLR mic inputs. It shows up as a USB webcam like normal.
Not any good one that does it in hardware out of the box that I know of. There are mod kits for CS lenses for c920/930/brio, if you can live with a tighter shot. If you've an compatible RX100/A6000 or similar laying around, then an Elgato Cam Link like hanselman's setup above might be the easiest option.
https://www.blackmagicdesign.com/products/blackmagicwebprese...