Using the Data Management API, you can ask for a folder content by calling GET https://developer.api.autodesk.com/data/v1/projects/{{PROJECT_ID}}/folders/{{SUB_FOLDER_ID}}/contents
The response will be a JSON file that contains info on extension type, like in below screenshot:
If the type is versions:autodesk.bim360:File
then it is not a bridged model.