ROS2 cam2image non default video device

edit

I don't believe you can (from here):

if (!burger_mode_) {
  // Initialize OpenCV video capture stream.
  // Always open device 0.
  cap.open(0);
  ..
}

The help output also doesn't seem to give the impression this is possible:

Usage:
 -h: This message.
 -r: Reliability QoS setting:
    0 - best effort
    1 - reliable (default)
 -d: Depth of the queue: only honored if used together with 'keep last'. 10 (default)
 -f: Publish frequency in Hz. 30 (default)
 -k: History QoS setting:
    0 - only store up to N samples, configurable via the queue depth (default)
    1 - keep all the samples
 -s: Camera stream:
    0 - Do not show the camera stream
    1 - Show the camera stream
 -x WIDTH and -y HEIGHT. Resolution.
    Please type v4l2-ctl --list-formats-ext
    to obtain a list of valid values.
 -b: produce images of burgers rather than connecting to a camera
 -t TOPIC: use topic TOPIC instead of the default