I have JSON objects that contain double values under the key value. However, sometimes those are nested, so data structures like this can exist:

[
    {
      "value": 0.1
    },
    {
      "value": {
        "value": 0.3
      }
    }
]

I’m trying to come up with an expression that would return only 0.1 and 0.3. Is this possible? The JSON is stored as JSONB field in a PostgreSQL database, if that makes any difference.