curl --request GET \
  --url https://api.headlesscommerce.io/v1/admin/inventory/{item_id} \
  --header 'Authorization: Bearer <token>'

{
  "id": "<string>",
  "variant_id": "<string>",
  "track_inventory": true,
  "allow_backorder": true,
  "safety_stock": 123,
  "on_hand": 123,
  "reserved": 123,
  "available": 123,
  "metadata": {}
}