Position to the top

Hey, nico13100 thanks for informing your issue. You can add a space between the product image by adding some code to your theme functions.php. you can change the offset top value as your need.

function ai1wsa_offset_top(){
?>
     <script>
          jQuery(document).ready(function () {
              jQuery('.woocommerce-product-gallery').stickr({
                  offsetTop: 30,
              });
          });
     </script>
<?php 
}
add_action( 'wp_footer', 'ai1wsa_offset_top' );

Unable the sticky position on mobiles issue will be fixed on my free time & release its next version.