only in patch2:
unchanged:
--- a/src/Plugin/DisplayVariant/LayoutBuilderDisplayVariant.php
+++ b/src/Plugin/DisplayVariant/LayoutBuilderDisplayVariant.php
@@ -4,15 +4,9 @@ namespace Drupal\page_manager\Plugin\DisplayVariant;
 
 use Drupal\Core\Display\VariantBase;
 use Drupal\Core\Form\FormStateInterface;
-use Drupal\Core\Plugin\Context\EntityContext;
-use Drupal\Core\Plugin\PluginFormInterface;
 use Drupal\ctools\Plugin\PluginWizardInterface;
-use Drupal\layout_builder\Form\DefaultsEntityForm;
 use Drupal\layout_builder\SectionStorage\SectionStorageTrait;
 use Drupal\page_manager\Form\LayoutBuilderForm;
-use Drupal\panels\Form\LayoutChangeRegions;
-use Drupal\panels\Form\LayoutChangeSettings;
-use Drupal\panels\Form\LayoutPluginSelector;
 
 /**
  * Provides a Layout Builder variant.
@@ -30,7 +24,11 @@ class LayoutBuilderDisplayVariant extends VariantBase implements PluginWizardInt
    * {@inheritdoc}
    */
   public function build() {
-    return ['#markup' => 'Hello'];
+    $build = [];
+    foreach ($this->getSections() as $delta => $section) {
+      $build[$delta] = $section->toRenderArray();
+    }
+    return $build;
   }
 
   public function buildConfigurationForm(array $form, FormStateInterface $form_state) {