<?php $attachment_ids = $product->get_gallery_image_ids(); ?>

<?php foreach ( $attachment_ids as $attachment_id ) { ?>
        <div class="product-welcome__slide"><a href="<?php echo wp_get_attachment_url( $attachment_id ); ?>" data-fancybox="product-gallery"><img src="<?php echo wp_get_attachment_url( $attachment_id ); ?>" alt=""></a></div>
<?php } ?>