poc.js

await window.Snipcart.api.cart.items.add({
      id: product.id,
      name: product.name,
      price: 10,
      url: '/',
      description: product.description,
      image: product.imageUrl,
      customFields: [
        {
          name: 'Frame color',
          options: [
            { name: 'black', priceModifier: 0 },
            { name: 'white', priceModifier: 1000 }
          ]
        }
      ],
      categories: [product.categoryId],
      hasTaxesIncluded: true
})