What is your suggestion?

Before creating the workspace after the user clicks submit on the workspace create form, we should post the parameters to the backend's/templateversions/:id/plan endpoint

Why do you want this feature?

This allows parameters to be validated before trying to create the workspace.

Are there any workarounds to get this functionality today?

Are you interested in submitting a PR for this?

50/50, it seems difficult because we'd have to show terminal output for the plan progress. We might need to overhaul the form a bit to integrate this :/