Coming in 2023 IR2 is the new MetrologyData API that will replace the standard public API.
All routes will now start wil https://hostname/dataloopcore/api/metrology/v1...

The $expand query can be used in a nested way and works with the majority of the different class properties. It does not however work when applied to the properties of Controls and MeasurementObjects depending from where the request begins. Indeed , if the initial request is not directly made from InspectorPieces then the MeasurementObjects and Controls will not be able to be listed. Therefore, in a request, if an $expand has been used upon the InspectorProjects or Workspaces to obtain the InspectorPieces and from there another $expand is used to obtain the MeasurementObjects and then the Controls, the MeasurementObjects and Controls will not be able to be listed, since they are not being accessed through InspectorPieces directly.

List of API features per release