WooCommerce - Only show grouped products parent at Shop page.

functions.php

//The idea is that we're modifying the query such that it will only show top-level items.... thus (in theory) nothing that has been assigned to a group, which would then have the group product's ID as the post_parent.
  add_action( 'woocommerce_product_query', 'musamam_product_query' );
  function musamam_product_query( $q ){
      $q->set( 'post_parent', 0 );
  }