Just try it!
Install the ms-python.python
VSIX from the market place page's "Download Extension" link. Then install it with code --install-extension <path to VSIX>
.
When I do that with a network connection, for some reason it installs the Python and Pylance extensions, but not the Jupyter extension (which is part of the Python extension pack). I'm not sure why that happens, but that's what happens for me. Maybe worth a bug report.
When I do that with no network connection, it just installs the Python package without installing any other extensions that are part of its extension pack. No error messages in the console. I found that surprising. Maybe worth a bug report.
You can look at the contents of the VSIX yourself. It's just a ZIP file. Use whatever program you have that can unzip such files. When I compare the Python VSIX with the Jupyter VSIX, I don't see the contents of the Jupyter VSIX in the Python VSIX, nor do I see any nested VSIX files or zip files, which indicates to me that no- an extension pack's VSIX does not contain the contents of the packed extensions' VSIXes.
If you want to install an extension pack without a network connection, you need to also manually grab the VSIXes for the extensions that are part of the extension pack.