You can add an "extensions.json" file inside of your workspace's .vscode directory with a list of recommended extensions[0]. The first time a new coworker joins the team, he only needs to pull the project and open it in VSCode, the editor will notice the file and prompt you to install the recommended extensions. The same thing can be done in the devcontainer.json file[1].

If you put the remote development extension in the "local" recommended, and the required extensions in the "remote" recommended, the requirements for the onboarding of a new team member boil down to "install VSCode, Docker and docker-compose"

[0] https://code.visualstudio.com/docs/editor/extension-gallery#...

[1] https://code.visualstudio.com/docs/remote/remote-overview