>> The most important parts of VSCode are not free software. > What do you mean by this?

The SSH remote connection stuff, the Pylance Python LSP (you are not allowed to use it - the binary - in any other editor but VS Code, not even the OSS Codium) and some other extensions are CSS.

"""Can I load Pylance in Code – OSS? Pylance is licensed for use in Microsoft products and services only, so can only be used on official Microsoft builds of Visual Studio Code and GitHub Codespaces."""

https://github.com/microsoft/pylance-release/blob/main/FAQ.m...