How to add a secondary product to the product page with AJAX API?

Technical Q&A
1

Hey,

I’m trying to add a secondary Add To Cart button which should add a different product (samples).

I tried using the AJAX API → Cart API to add the product https://shopify.dev/docs/themes/ajax-api/reference/cart#post-cart-add-js

Tried to call the API from the developer console and from an script tag, but I receive a 404 error

let formData = {
 'items': [{
  'id': $ProductID,
  'quantity': 1
  }]
};

fetch('/cart/add.js', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json'
  },
  body: JSON.stringify(formData)
})
.then(response => {
  return response.json();
})
.catch((error) => {
  console.error('Error:', error);
});

After that I tried to add a second {% form ‘product’ %} tag after/outside the standard Add to cart form. But when I add the form below, the submit from the original add to cart also adds the sample product instead of the original one

Maybe someone can help with either of approaches