Accessing attributes referenceId in REST API Composite call

Hi Ohana,

I am writing a composite call to create products and add them to strandard Pricebook.

    {
  "allOrNone": true,
  "collateSubrequests": false,
  "compositeRequest": [
                {
                  "method": "GET",
                  "referenceId": "refProductRecordType",
                  "url": "/services/data/v56.0/query/?q=SELECT+id+FROM+RecordType+WHERE+SobjectType+='Product2'+AND+DeveloperName+='Product'"
                },
                {
                  "method": "PATCH",
                  "referenceId": "refProdList",
                  "url": "/services/data/v56.0/composite/sobjects/Product2/External_Id__c", 
                  "body": {
                    "allOrNone": true,
                    "records": [
                              {       "attributes" : {"type" : "Product2", "referenceId" : "prod0"},
                                      "RecordTypeId": "@{refProductRecordType.records[0].Id}",
                                      "Name":"product 1",                                                                 
                                       "External_Id__c" : "12121",
                                       "Description" : "bla bla",
                                       "IsActive" : true
                                    }
                                ]
                          }
                  },
                  {
                    "method": "GET",
                    "referenceId": "refPricebook",
                    "url": "/services/data/v56.0/query/?q=SELECT+id+FROM+Pricebook2+WHERE+Name+='Standard Price Book'+AND+IsStandard+=+true"
                  },
                  {
                    "method": "POST",
                    "referenceId": "refPbe",
                    "url": "/services/data/v56.0/sobjects/PricebookEntry",
                    "body": {
                            "Pricebook2Id": "@{refPricebook.records[0].Id}",
                            "Product2Id":"@{prod0.Id}",
                            "UnitPrice" : 0.00,
                            "IsActive" : true
                          }
                  }           
  ]
}

When I try executing this composite POST call, I get error :

    {
    "body" : [ {
      "errorCode" : "PROCESSING_HALTED",
      "message" : "Could not find the referenced operation prod0"
    } ],
    "httpHeaders" : { },
    "httpStatusCode" : 400,
    "referenceId" : "refPbe"
  } 

I am trying to access the referenceId "prod0", but not sure how to get it because it's kind of a nested reference or if it's possible to access such a reference.

Any help would be appreciated.

Thanks!