I’m using version 1.2.9. In the fetchDevice function, it’s querying by ID to retrieve all device information, but that increases the system’s bandwidth usage. Is it possible to retrieve only the necessary information instead of fetching everything?"
What are you actually trying to do? You appear to be trying to consume a function internal to GenieACS.
If you are trying to query GenieACS from an external system, only the API will is supported.