The ONSCREEN Spark allows you to switch to the Spark when a call is coming in, and switch back to another HDMI port when the call is ended. To do this, go to your Spark tab.
From this screen, click "Set HDMI Ports" and you will see the following screen, where you can set the ports you want to switch to and from:
Now, whenever you make or answer a call, your TV will switch to the HDMI port designated for the Spark. When the call ends, it will switch back to the port you chose. This also applies to Zoom meetings.