Hi,
You may try
gst-launch-1.0 v4l2src device=/dev/video0 io-mode=2 ! image/jpeg, width=(int)3264, height=(int)2448 ! nvjpegdec ! video/x-raw ! videoconvert ! video/x-raw,format=BGR ! fakesink
If above command works, you can then try
cap = cv2.VideoCapture('v4l2src device=/dev/video0 io-mode=2 ! image/jpeg, width=(int)3264, height=(int)2448 ! nvjpegdec ! video/x-raw ! videoconvert ! video/x-raw,format=BGR ! appsink', cv2.CAP_GSTREAMER)