paragraph_split.module

<?php

use Drupal\Core\Entity\EntityInterface;
use Drupal\paragraphs\Entity\Paragraph;
use Drupal\user\Entity\User;
use Drupal\node\Entity\Node;

/** 
 * Implements hook_ENTITY_TYPE_insert() for 'nodes'
 * When a node is created, with content in the temporary field, create the associated paragraph instead
 */
function paragraph_split_node_insert(EntityInterface $node) {
    //If node content type is node_type
    if ($node->getType() == 'node_type') {
        if (!$node->get('field_title')->isEmpty) {
            $new_paragraphs = array();

            $count = count($node->get('field_title'));
            for ($k = 0; $k < $count; $k++) {

                //This is needed to handle when there is a title without a matching description
                $desc = (empty($node->get('field_description')[$k])) ? '' : $node->get('field_description')[$k]->getString();

                //Create new paragraph entity
                $paragraph = Paragraph::create([
                    'type' => 'paragraph_type',
                    'field_title' => $node->get('field_title')[$k],
                    'field_description' => $desc,
                    'uid' => 1,
                ]);
                $paragraph->save();

                //Add the new paragraph to the array
                array_push($new_paragraphs,array(
                    'target_id' => $paragraph->id(),
                    'target_revision_id' => $paragraph->getRevisionId(),
                ));
            }

            //Overrides if there was already one in place, which there shouldn't be in this context of an import
            $node->field_paragraph_reference = $new_paragraphs;
        }

        $node->save();
    }
}