<div class="x-slider_slide splide__slide">
  <?php echo the_post_thumbnail( 'medium_large' ); ?>
</div>

<?php
global $product;

$attachment_ids = $product->get_gallery_image_ids();

if ( $attachment_ids ) {
	foreach( $attachment_ids as $attachment_id ) {
		$image = wp_get_attachment_image_src( $attachment_id, 'medium_large' );
		$image_url = $image[0];
		$image_alt = get_post_meta( $attachment_id, '_wp_attachment_image_alt', true );
		?>

		<div class="x-slider_slide splide__slide">
			<img src="<?php echo $image_url; ?>" alt="<?php echo $image_alt; ?>">
		</div>
<?php }
}
?>