I recently made a GitHub Codespaces devcontainer config for discourse plugins that will automatically clone the discourse core repo around the plugin, generating a fresh discourse dev environment for each plugin.
It extends from the existing config for discourse core, preserving the automated setup and task shortcuts for starting a new build.
Here is a commit in one of my repos that contain the related configs for it.
Unfortunately, to be able to run build tasks via shortcuts, the user lands on the /discourse directory, so the plugin repo is not immediately available. However, users can just navigate to their respective repos plugins in the /discourse/plugins directory, or add it to the explorer as a workspace folder via the command palette. Adding workspace folder will also expose the plugin repo to the vscode source control Git UI.
Adding the workspace folder can probably be done programmatically in vscode, but I haven’t tested it.