Building specific query in dv360 API or Doubleclickbidmanager

Question

I am needing assistance with building a report that can be run with an automated call and with a specified youtube_channel_id. The screenshot provided is the report that I want to be run as built in the DV360 UI. I am having trouble finding a way to add dimensions to the API call to add category as a dimension. enter image description here This report should show the breakdown of impressions (and cookies) by category for a given youtube channel (in this example: Top Gear). I also have the current method run without the correct dimensions set (there is apparently no dimensions tag in the API from my understanding), which just returns the total impression (and cookies) count for the last 7 days, as run with a doubleclickbidmanager API call

{
  "metadata": {
    "title": "Test",
    "dataRange": {
      "range": "LAST_7_DAYS"
    },
    "format": "CSV"
  },
  "params": {
    "filters": [
      {
        "type": "FILTER_PARTNER",
        "value": "XXXXXX"
      },
      {
        "type": "FILTER_CHANNEL_ID",
        "value": "UCjOl2AUblVmg2rA_cRgZkFg"
      }
    ],
    "metrics": [
      "METRIC_IMPRESSIONS"
    ],
    "groupBys": [
      "FILTER_PARTNER",
      "FILTER_CHANNEL_ID"
    ]
  }
}

Is there any way to do this, if so can anyone give me some help. Thanks Regardless

See above for the issue and what i have tried/have working