Nintendo initially stated that the Switch 2 would be compatible with most USB webcams; however, testing revealed that Pixel smartphones could not function as webcams at launch, despite enabling the USB webcam mode introduced with Android 14. Users of the Switch 2 later discovered that Android and iPhone models could serve as webcams, but only when utilizing additional USB-C to HDMI adapters and HDMI capture cables.
Recent developments have changed this situation. In testing with a Pixel 9 Pro connected directly to the Switch 2’s USB-C port using a single cable, it was confirmed that the smartphone could be utilized as a webcam after selecting the “Webcam” mode in the USB preferences. This functionality enabled the use of GameChat, which allows players of games like Mario Kart World to communicate with others and see their competitors over a livestream if equipped with a webcam.
It remains unclear whether updates from Google or Nintendo contributed to this enhanced compatibility. The Pixel 9 Pro used in the tests was operating on the December release of Android 16. This improvement may be particularly beneficial for users who travel frequently with their Switch 2 and prefer not to carry a secondary webcam.
Source: https://www.theverge.com/news/839133/google-pixel-smartphone-nintendo-switch-2-webcam