Hi, i just want to put here what helped me
// This function was added from the Properties & Events panel. To learn more, visit Velo: Working with the Properties & Events Panel | Help Center | Wix.com
// Add your code for this event here:
export function AddToCartButton1_click(event, $w) {
const productId = $w( ‘#dynamicDataset’ ).getCurrentItem()._id;
const myValue = $w( “#dropdown1” ).value;
const choices = { “Size” : myValue };
$w( ‘#shoppingCartIcon1’ ).addToCart( productId, 1 , {choices} )
}