data-product_id

I am creating custom buy now button for variation products which adds the variation directly to checkout or cart.
I am using
echo ‘get_id().'” class=”buy-now button”>Buy Now‘; while showing the button but it is getting the product id instead of variation id. but in add to cart code via inspect element i do see data-product_id which actually contains the correct variation id. how to add that field to the custom buy now button?

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