I've the next query to get the most recent comments:

global $wpdb;
  $sql = "SELECT DISTINCT ID, post_title, post_password, comment_ID, comment_post_ID, comment_author, comment_date_gmt, comment_approved, comment_type,comment_author_url, SUBSTRING(comment_content,1,30) AS com_excerpt FROM $wpdb->comments LEFT OUTER JOIN $wpdb->posts ON ($wpdb->comments.comment_post_ID = $wpdb->posts.ID) WHERE comment_approved = '1' AND comment_type = '' AND post_password = '' ORDER BY comment_date_gmt DESC LIMIT 10";

  $comments = $wpdb->get_results($sql);

I should also obtain the title(slug) from the publish for every comment, without managing a query for every comment. Are you able to advise a modification towards the above query to do this? Even better, can one do that using built-in Wordpress functions?

Essentially I want:

$comments = array ( 'comment_object' => ... , 'post_name' => ... )

From the own Recent Comments code with minor edits:

/**
 * @return object
 */ 
function recent_comments_query($limit)
{
    global $wpdb;

    $sql = "SELECT DISTINCT ID,
                post_title,
                post_name, // <- post name
                post_password,
                comment_ID,
                comment_post_ID,
                comment_author AS author,
                comment_date_gmt,
                comment_approved,
                comment_type,
                comment_author_url AS url,
            SUBSTRING(comment_content, 1, 200)
                AS comment_content
            FROM $wpdb->comments
            LEFT OUTER JOIN $wpdb->posts
                ON (
                    $wpdb->comments.comment_post_ID = $wpdb->posts.ID
                )
            WHERE comment_approved = '1'
                AND comment_type   = ''
                AND post_password  = ''
            ORDER BY comment_date_gmt DESC
            LIMIT $limit";

     return $wpdb->get_results($sql);
}

You’ll return an item with $limit results or NULL.