Can I show all the template files that are being used on my site?

by

this would add a column with the page template file name into the ‘Pages’ in the dashboard:

// ONLY WORDPRESS DEFAULT PAGES
add_filter('manage_page_posts_columns', 'custom_admin_columns_head', 10);
add_action('manage_page_posts_custom_column', 'custom_admin_columns_content', 10, 2);

// ADD NEW COLUMN
function custom_admin_columns_head($defaults) {
    $defaults['page_template_file'] = 'Page Template File';
    return $defaults;
}

// SHOW THE PAGE TEMPLATE FILE NAME
function custom_admin_columns_content($column_name, $post_ID) {
    if ($column_name == 'page_template_file') {
        $page_template_file = get_post_meta( $post_ID, '_wp_page_template', true );
            echo ($page_template_file ? $page_template_file : '-');
    }
}

based on:
https://codex.wordpress.org/Function_Reference/get_page_template_slug
https://code.tutsplus.com/articles/add-a-custom-column-in-posts-and-custom-post-types-admin-screen–wp-24934