curl --request GET \
  --url https://api.mysubwallet.ng/api/esim/catalog/countries \
  --header 'Authorization: <api-key>'

{
  "status": "success",
  "data": [
    {
      "id": 724,
      "name": "Spain",
      "country_code": "ES",
      "image_url": "https://flagcdn.com/h60/es.png"
    }
  ]
}