curl --request GET \
  --url https://eu1.api.matillion.com/dpc/v1/projects/{projectId}/variables/{variableName}/environment-overrides \
  --header 'Authorization: Bearer <token>'

{
  "overrides": [
    {
      "environmentName": "<string>",
      "value": "<unknown>"
    }
  ],
  "variable": {
    "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "name": "<string>",
    "type": "NUMBER"
  }
}