Frontend.php

<?php foreach ($controller->getItems() as $item) : ?>
    <p><?php echo $item['title']; ?></p>
<?php endforeach; ?>

setup.php

<?php

namespace App;

use Roots\Sage\Container;
use Roots\Sage\Assets\JsonManifest;
use Roots\Sage\Template\Blade;
use Roots\Sage\Template\BladeProvider;
use App\Blocks\Testimonial\Testimonial;

/**
 * Theme assets
 */
add_action('wp_enqueue_scripts', function () {
    wp_enqueue_style('material-icons', 'https://fonts.googleapis.com/icon?family=Material+Icons', false, null);
    wp_enqueue_style('sage/main.css', asset_path('styles/main.css'), ['material-icons'], false, null);
    // wp_enqueue_script('jquery', 'https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js', ['jquery'], null, true);
    wp_enqueue_script('sage/main.js', asset_path('scripts/main.js'), ['jquery'], null, true);

    if (is_single() && comments_open() && get_option('thread_comments')) {
        wp_enqueue_script('comment-reply');
    }
}, 100);

/**
 * Theme setup
 */
add_action('after_setup_theme', function () {
    /**
     * Enable features from Soil when plugin is activated
     * @link https://roots.io/plugins/soil/
     */
    add_theme_support('soil-clean-up');
    add_theme_support('soil-jquery-cdn');
    add_theme_support('soil-nav-walker');
    add_theme_support('soil-nice-search');
    add_theme_support('soil-relative-urls');

    /**
     * Enable plugins to manage the document title
     * @link https://developer.wordpress.org/reference/functions/add_theme_support/#title-tag
     */
    add_theme_support('title-tag');

    /**
     * Register navigation menus
     * @link https://developer.wordpress.org/reference/functions/register_nav_menus/
     */
    register_nav_menus([
        'primary_navigation' => __('Primary Navigation', 'sage')
    ]);

    /**
     * Enable post thumbnails
     * @link https://developer.wordpress.org/themes/functionality/featured-images-post-thumbnails/
     */
    add_theme_support('post-thumbnails');

    /**
     * Enable HTML5 markup support
     * @link https://developer.wordpress.org/reference/functions/add_theme_support/#html5
     */
    add_theme_support('html5', ['caption', 'comment-form', 'comment-list', 'gallery', 'search-form']);

    /**
     * Enable selective refresh for widgets in customizer
     * @link https://developer.wordpress.org/themes/advanced-topics/customizer-api/#theme-support-in-sidebars
     */
    add_theme_support('customize-selective-refresh-widgets');

    /**
     * Use main stylesheet for visual editor
     * @see resources/assets/styles/layouts/_tinymce.scss
     */
    add_editor_style(asset_path('styles/main.css'));
}, 20);

/**
 * Register sidebars
 */
add_action('widgets_init', function () {
    $config = [
        'before_widget' => '<section class="widget %1$s %2$s">',
        'after_widget'  => '</section>',
        'before_title'  => '<h3>',
        'after_title'   => '</h3>'
    ];
    register_sidebar([
        'name'          => __('Primary', 'sage'),
        'id'            => 'sidebar-primary'
    ] + $config);
    register_sidebar([
        'name'          => __('Footer', 'sage'),
        'id'            => 'sidebar-footer'
    ] + $config);
});

/**
 * Updates the `$post` variable on each iteration of the loop.
 * Note: updated value is only available for subsequently loaded views, such as partials
 */
add_action('the_post', function ($post) {
    sage('blade')->share('post', $post);
});

/**
 * Setup Sage options
 */
add_action('after_setup_theme', function () {
    /**
     * Add JsonManifest to Sage container
     */
    sage()->singleton('sage.assets', function () {
        return new JsonManifest(config('assets.manifest'), config('assets.uri'));
    });

    /**
     * Add Blade to Sage container
     */
    sage()->singleton('sage.blade', function (Container $app) {
        $cachePath = config('view.compiled');
        if (!file_exists($cachePath)) {
            wp_mkdir_p($cachePath);
        }
        (new BladeProvider($app))->register();
        return new Blade($app['view']);
    });

    /**
     * Create @asset() Blade directive
     */
    sage('blade')->compiler()->directive('asset', function ($asset) {
        return "<?= " . __NAMESPACE__ . "\\asset_path({$asset}); ?>";
    });
});


/**
 * Register ACF Gutenblocks
 */
add_filter('acf_gutenblocks/blocks', function (array $blocks): array {
    $new_blocks = [
        Testimonial::class,
    ];
    return array_merge($blocks, $new_blocks);
});

Testimonial.php

<?php

declare(strict_types=1);

namespace App\Blocks\Testimonial;

use Itineris\AcfGutenblocks\AbstractBlock;

class Testimonial extends AbstractBlock
{
    public function __construct()
    {
        parent::__construct([
            'title' => __('Testimonial', 'fabric'),
            'description' => __('Testimonial description', 'fabric'),
            'category' => 'formatting',
            // Other valid acf_register_block() settings
        ]);
    }

    public function getItems(): array
    {
        $items = [];
        foreach (get_field('list_items') as $item) {
            if ($item['enabled']) {
                $items[] = $item['list_item'];
            }
        }
        return $items;
    }

    protected function registerFields(): array
    {
        $testimonial = new FieldsBuilder('testimonial');

        $testimonial
            ->setLocation('block', '==', 'acf/testimonial');

        $testimonial
            ->addText('quote')
            ->addText('cite')
            ->addRepeater('list_items')
                ->addText('list_item')
                ->addTrueFalse('enabled', [
                    'ui' => 1,
                    'default_value' => 1,
                ])
            ->endRepeater();

        return $testimonial->build();
    }
    
}