[Jetpack] A little plugin to strip down Jetpack until all what's left is the Markdown block

plugin.php

<?php
/**
 * Plugin Name: Markdown from Jetpack
 * Plugin URI: https://jetpack.com
 * Description: Use only the Markdown block in Jetpack, nothing else. This must be installed in addition to the Jetpack plugin.
 * Author: Automattic
 * Version: 1.0.0
 * Author URI: https://jetpack.com
 * License: GPL2+
 * Requires at least: 5.5
 * Requires PHP: 5.6
 */

/*
 * Disable Jetpack's connection to WordPress.com.
 * Allows you to use all features that do not require a connection to WordPress.com.
 */
add_filter( 'jetpack_offline_mode', '__return_true' );

/*
 * Only load the Markdown block.
 * Other blocks in Jetpack will not be available.
 */
add_filter( 'jetpack_set_available_extensions', function() { return [ 'markdown' ]; } );

/*
 * Do not load extra tools available in Jetpack,
 * such as Facebook and Instagram embeds for sites that need them.
 */
add_filter( 'jetpack_tools_to_include', '__return_empty_array' );

/*
 * Do not let any module be available in the Jetpack UI,
 * and do not allow one to turn modules on in any way.
 */
add_filter( 'jetpack_get_default_modules', '__return_empty_array' );
add_filter( 'jetpack_get_available_modules', '__return_empty_array' );

/*
 * In fact, let's remove the Jetpack menu altogether.
 * Note: you don't want to do that if other plugins on your site (such as the Akismet plugin) nest their menu items
 * under the Jetpack main menu.
 * In such cases, you'd want to remove the menu item only for non-admins for example.
 */
add_action( 'admin_menu', function() {
	remove_menu_page( 'jetpack' ); 
}, 999 );