As of vscode 1.69 Insiders, see https://stackoverflow.com/a/72875272/836330 for "settings profiles" which allow you to have different sets of extensions for different projects. Also https://github.com/microsoft/vscode-docs/blob/vnext/release-notes/v1_69.md#settings-profiles
There is an example there specifically about setting up different environments for different languages -
A Settings Profile comprises of settings, keyboard shortcuts,
extensions, state, tasks, and snippets. You can customize VS Code for
different development environments like Web, Machine Learning, or for
multiple programming language classrooms like Python, Java or for
personal modes like Work or Demo and save them as Settings Profiles.
You can open multiple workspaces (folders) with different profiles
simultaneously based on the projects you are working on or the
classroom you are attending to or when you are presenting.
[Previously, suggest using the above instead.]
This is the same issue: https://github.com/microsoft/vscode/issues/98093 (Unique Settings for Different Programming Environments)
There is an intriguing comment there about using the Settings Sync extension (not the built-in settings sync) to create different "profiles" - including different sets of extensions - for different programming environments, not necessarily different machines.
And see Profile Switcher.