Simple dashboard widget for listing WordPress multisite sites, and accompanying shortcode for the front end.

network-lister.php

<?php
/*
Plugin Name: Network Lister
Plugin URI: https://gist.github.com/webaware/b914967f0ce8110c775cd12ddc546283
Update URI: network-lister
Description: simple dashboard widget for listing network sites
Version: 0.0.5
Author: WebAware
Author URI: https://shop.webaware.com.au/
*/

/*
copyright (c) 2018-2023 WebAware Pty Ltd

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
*/

namespace webaware\network_lister;

if (!defined('ABSPATH')) {
	exit;
}

/**
 * get a list of all sites on the network
 */
function get_list(bool $for_admin) : string {
	$output = '';

	$current_site_id = get_current_blog_id();
	$sites = get_sites();
	if (is_array($sites)) {
		$list = [];
		$template = $for_admin ? '<li><a href="%s/wp-admin/"%s>%s — %s</a></li>' : '<li><a href="%s/"%s>%s — %s</a></li>';
		foreach ($sites as $site) {
			$details = get_blog_details($site->blog_id);
			$style = $current_site_id == $site->blog_id ? ' style="font-weight:bold"' : '';
			$list[$details->blogname] = sprintf($template,
											esc_url(set_url_scheme($details->siteurl)),
											$style,
											esc_html($details->blogname),
											esc_html($details->blog_id));
		}

		uksort($list, 'strcasecmp');

		$output = '<ul>' . implode('', $list) . '</ul>';
	}

	return $output;
}

/**
 * show list widget on admin dashboard
 */
function show_lister_widget() : void {
	echo get_list(true);
}

/**
 * create the new dashboard widget
 */
function add_lister_widget() : void {
	wp_add_dashboard_widget('network-lister', 'Network List', __NAMESPACE__ . '\\show_lister_widget');
}

add_action('wp_dashboard_setup', __NAMESPACE__ . '\\add_lister_widget');
add_action('wp_network_dashboard_setup', __NAMESPACE__ . '\\add_lister_widget');

/**
 * add shortcode for network list
 */
add_shortcode('network_lister', function() : string {
	return get_list(false);
});

/**
 * show the current site ID on every page footer
 */
add_filter('admin_footer_text', function(string $footer_text) : string {
	$footer_text .= ' &bull; blog_id = ' . get_current_blog_id();

	return $footer_text;
}, 20);