https://axil.github.io/how-to-open-ipynb-file-with-one-doubleclick-on-windows.html
Can install this inside conda env:
pip install nbopen
python -m nbopen.install_win
This will reuse existing jupyter server if possible (=if it is already launched in the same dir).
Then two options: (I did the second)
Run this command in cmd.exe under administrator privileges:
assoc .whl=jupyter& ftype jupyter=cmd.exe /c jupyter-notebook "%1"
Alternatively, a slightly different line can be copied into a assoc_ipynb.bat file and executed through 'Run as administrator':
assoc .whl=jupyter& ftype jupyter=cmd /c jupyter-notebook "%%1"
PS jupyter-notebook.exe is assumed to be in the PATH.
to close open notebooks
open conda prompt any env
jupyter notebook list
jupyter notebook stop 8888