curl --request POST \
  --url https://api.headlesscommerce.io/v1/admin/products/{id}/variants \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "price": {
    "amount": 123,
    "currency": "<string>"
  },
  "sku": "<string>",
  "barcode": "<string>",
  "weight": 123,
  "options": {},
  "metadata": {}
}
'

{
  "id": "<string>",
  "product_id": "<string>",
  "sku": "<string>",
  "barcode": "<string>",
  "price": {
    "amount": 123,
    "currency": "<string>"
  },
  "compare_at_price": {
    "amount": 123,
    "currency": "<string>"
  },
  "cost_price": {
    "amount": 123,
    "currency": "<string>"
  },
  "weight": 123,
  "is_active": true,
  "option_values": [
    {
      "id": "<string>",
      "value": "<string>",
      "position": 123
    }
  ],
  "images": [
    {
      "id": "<string>",
      "url": "<string>",
      "alt_text": "<string>",
      "position": 123,
      "width": 123,
      "height": 123
    }
  ],
  "inventory": {
    "id": "<string>",
    "variant_id": "<string>",
    "track_inventory": true,
    "allow_backorder": true,
    "safety_stock": 123,
    "on_hand": 123,
    "reserved": 123,
    "available": 123,
    "metadata": {}
  },
  "metadata": {},
  "created_at": "2023-11-07T05:31:56Z",
  "updated_at": "2023-11-07T05:31:56Z"
}