About getting the number of free operators available for chat in the queue

[Ueno]

I would like to get the number of available operators who can chat in the queue with the API below.
I tried to get it by specifying the parameters listed at the bottom, but I can't extract it.
"mediaType" doesn't seem to work and I'm not sure how the API works.

Is it possible to get a limited number of users who can chat using this API?
Also, if it's not possible, please let me know the alternative API.

POST /api/v2/analytics/queues/observations/query

{
  "filter": {
    "type": "and",
    "clauses": [
      {
        "type": "and",
        "predicates": [
          {
            "dimension": "queueId",
            "value": "XXXXX"
          },
          {
            "dimension": "mediaType",
            "value": "chat"
          }
        ]
      }
    ]
  },
  "metrics": [
    "oOnQueueUsers"
  ],
  "detailMetrics": [
    "oActiveUsers"
  ]
}

[tim.smith]

You should be able to get this information if you're using extremely basic routing. Meaning agents are only in a single queue and any agent in the queue can handle anything that comes in to it with no restrictions by skills or bullseye or anything. There's not a way to get a direct count of agents "available" for a subset of a queue. A better practice may be to use EWT https://developer.genesys.cloud/routing/routing/estimatedwaittime-v2