The Raspberry Pi 400 doesn't have the same CSI camera connector as the Raspberry Pi 4, so it's not possible to use a Camera Module or High-Quality Camera.
You can, however, use USB cameras using the USB ports on the back of the Pi 400 keyboard.
All of our current Raspberry Pi compatible USB cameras can be found here: https://thepihut.com/collections/raspberry-pi-usb-cameras