In the Step Templates there is a tab that shows where that step template is used. I don’t see this on Variable Sets. Is there a way other than attempting to delete the variable set that shows you where they are used?
There isn’t really a way to traverse the usage from the Variable Set no.
They are linked from the projects, so if you want to write an API script you could load the projects (i.e. GET /api/projects/my-project) and see the IncludedLibraryVariableSetIds as part of that document.