Separate Page for Post Comments

The code below designed as a plugin and creates a separate comments page for single post of the site. A new page .../comments/ appears for each post, it displays comments of the post.

Let's do the stuff - create a normal WordPress plugin.

1. Create a plugin folder comments-page.
2. Create inside the file comments-page.php.
3. Activate the plugin. OR You can add the code in theme's function.php.

<?php

/**
 * Plugin Name: Kama Post Comments Single Page
 * Description: Creates single page for post comments.
 * Version: 1.0
 * Author: Kama
 * Author URI: http://wp-kama.com
 */

$Kama_Separate_Comments_Page = new Kama_Separate_Comments_Page;
$Kama_Separate_Comments_Page->init();

class Kama_Separate_Comments_Page {

	static $page_title_patt = "Comments for %s";

	function init(){

		add_filter( 'query_vars',       [ $this, 'query_vars' ] );
		add_action( 'init',             [ $this, 'add_endpoint' ] );
		add_action( 'single_template',  [ $this, 'template_redirect' ] );
		add_filter( 'get_comment_link', [ $this, 'get_comment_link' ] );
		add_filter( 'wp_title',         [ $this, 'wp_title' ], 10, 1 );

		register_activation_hook( __FILE__,   [ $this, 'activate'] );
		register_deactivation_hook( __FILE__, [ $this, 'deactivate'] );
	}

	function query_vars( $vars ){
		$vars[] = 'comments';

		return $vars;
	}

	# Add a /comments/ page to all post permalinks
	function add_endpoint(){
		add_rewrite_endpoint( 'comments', EP_PERMALINK );
	}

	# Template file for the /comments/ permalink
	function template_redirect( $templates = '' ){
		global $wp_query;

		if( ! isset( $wp_query->query['comments'] ) )
			return $templates;

		$templates = locate_template( 'comments-page-template.php', false );

		if( ! $templates ){
			$templates = __DIR__ . '/comments-page-template.php';
		}

		return $templates;
	}

	# Fix comment permalinks
	function get_comment_link( $url ){
		$urlparts = explode( '#', $url );

		return untrailingslashit( $urlparts[0] ) . '/comments/#' . $urlparts[1];
	}

	# Fix the page title
	function wp_title( $title ){
		global $wp_query;

		if( isset( $wp_query->query['comments'] ) )
			$title = sprintf( self::$page_title_patt, $title );

		return $title;
	}

	function activate(){
		$this->add_endpoint();
		flush_rewrite_rules();
	}

	function deactivate(){
		flush_rewrite_rules();
	}

}

Now you need to create a template file. It will be responsible for the output of our page with pos tcomments. The file should be named comments-page-template.php and should be placd in the plugin folder or in the current theme folder (child or parent).

Fix code below for your theme.

<?php
get_header();
?>

<article id="post" class="hentry <?= post_class() ?>">

	<h1 class="entry-title">Comments: "<a href="<?php the_permalink(); ?>"><?php the_title(); ?></a>"</h1>

	<div class="entry-content">

		<?php

		wp_list_comments( 'reverse_top_level=false', get_comments([ 'post_id'=> $post->ID ]) );

		comment_form();

		?>

	</div>

</article>

<?php

get_footer();

IMPORTANT! Now you need to go to the "Permalinks" admin page. It neede for reset the WP rewrite rules.

That's it! A separate page for post comments is ready. Add /comments/ at the end of the URL of the current post and get to the post comments page.