List of Access Keys from Output Values after ARM Template Deployment

FunctionApp.json

{
  "variables": {
    "functionApp": {
      "name": "my-function-app",
      "functionName": "my-function"
    },
    "resourceId": "[resourceId('Microsoft.Web/sites/functions', variables('functionApp').name, variables('functionApp').functionName)]",
    "apiVersion": "[providers('Microsoft.Web', 'sites').apiVersions[0]]"
  },
  "resources": [],
  "outputs": {
    "functionKey": {
      "type": "string",
      "value": "[listSecrets(variables('resourceId'), variables('apiVersion')).key]"
    }
  }
}