curl --request POST \
  --url https://api.merchantops.ai/api/products/{product_key}/variants/generate-matrix \
  --header 'Content-Type: application/json' \
  --data '
{
  "axes": {},
  "same_for_all_defaults": {}
}
'

{
  "preview": [
    {}
  ],
  "total_count": 123
}