You can also download the *.vsix file of the desired extension from either Github or Microsoft’s extension marketplace and install it manually by clicking on “Install from VSIX” in the Extensions menu.

This obviously doesn’t solve the update problem and it is also questionable if this is in terms with the “Microsoft Terms of Use” of the extension.

Does codium handle updates for the extensions?

or just use the vscode marketplace in codium…

you can also just use openvsix, which actually contains everything you’ll ever need

This works until you have debug .NET.