Search Result Preview in the Block Editor

add_action( 'enqueue_block_editor_assets', function () {
    $screen = get_current_screen();
    if ( ! $screen || 'post' !== $screen->base ) {
        return;
    }

    wp_register_script( 'wpide-serp-preview', false, array( 'wp-plugins', 'wp-element', 'wp-data', 'wp-editor' ), '1.0', true );
    wp_enqueue_script( 'wpide-serp-preview' );
    wp_add_inline_script( 'wpide-serp-preview', 'var wpideSerp = ' . wp_json_encode( array( 'site' => get_bloginfo( 'name' ), 'home' => home_url( '/' ) ) ) . ';' . <<<'JS'
( function ( wp ) {
    var el = wp.element.createElement;
    var Panel = ( wp.editor && wp.editor.PluginDocumentSettingPanel ) || ( wp.editPost && wp.editPost.PluginDocumentSettingPanel );
    if ( ! Panel ) { return; }

    function clip( text, max ) { return text.length > max ? text.slice( 0, max - 1 ).replace( /\s+\S*$/, '' ) + '…' : text; }

    function SerpPreview() {
        var data = wp.data.useSelect( function ( select ) {
            var editor = select( 'core/editor' );
            return {
                title: editor.getEditedPostAttribute( 'title' ) || '',
                excerpt: editor.getEditedPostAttribute( 'excerpt' ) || '',
                content: editor.getEditedPostAttribute( 'content' ) || '',
                link: editor.getPermalink() || wpideSerp.home
            };
        }, [] );
        var text = ( data.excerpt || data.content ).replace( /<[^>]+>/g, ' ' ).replace( /\s+/g, ' ' ).trim();
        var url = data.link.replace( /^https?:\/\//, '' ).replace( /\/$/, '' ).split( '/' ).join( ' › ' );

        return el( Panel, { name: 'wpide-serp-preview', title: 'Search result preview' },
            el( 'div', { style: { fontFamily: 'arial, sans-serif', lineHeight: 1.4 } },
                el( 'div', { style: { fontSize: '12px', color: '#4d5156' } }, wpideSerp.site + ' · ' + url ),
                el( 'div', { style: { fontSize: '17px', color: '#1a0dab', margin: '2px 0' } }, clip( ( data.title || '(no title)' ) + ' - ' + wpideSerp.site, 62 ) ),
                el( 'div', { style: { fontSize: '13px', color: '#4d5156' } }, clip( text || 'Add an excerpt to control this text.', 158 ) )
            )
        );
    }

    wp.plugins.registerPlugin( 'wpide-serp-preview', { render: SerpPreview } );
} )( window.wp );
JS
    );
} );