That's not what I'm asking. Any teleconferencing app lets you do that.

Specifically, in Zoom, I can share from a second camera. This could be a USB Webcam, or a USB/PCIe HDMI Capture Card, or OBS' Virtual Camera plugin. I prefer the latter as it gives me lots of flexibility, can present full screen Keynote/Powerpoints while keeping my desktop/windows arranged how I like, with presenter notes up, and switch to a USB HDMI capture card with the click of a button in OBS, with custom text, transitions, etc.

Last I checked, Teams assumed any camera input was for the "Camera", not for the screen share.