we only have auto generated stubs for cv2. we need real stub for anything more than the first level completion to work.

Given that opencv can now generates python stubs and opencv-python has been updated to ship them, you can try the in-development version using pip install git+https://github.com/opencv/opencv-python.git.

You can set the appropriate environment variables first if you'd like to install a specific package (like headless, contrib or healdless-contrib):

ENABLE_CONTRIB=1
ENABLE_HEADLESS=1

It should work as-is with pyright and mypy, but for Pylance you'll have to remove the bundled stubs every time you update the extension. It can be found at: %HOMEPATH%\.vscode\extensions\ms-python.vscode-pylance-<VERSION>\dist\bundled\stubs\cv2-stubs (where <VERSION> is your current Pylance version).

If the issue persists, you can raise it upstream.