There are a few basic things a developer needs to do in a custom module.... node creation is top of my list.

This code is within a controller that is part of a custom module. I won't explain how to build the module but this code is within a file called ReportController.php.

The basic file code is:

namespace Drupal\mycustommodule\Controller;

use Drupal\Core\Controller\ControllerBase;
use Drupal\node\Entity\Node;

class ReportController extends ControllerBase {

   // The main controller code goes in here

}

I put the node creation code into a separate 'protected' function which are called within the main 'public' function like this:

public function mainReportFunction() {
    $newVideoNode = $this->createVideoNode($video);
}

I won't explain how the following functions work but they're basic SQL SELECT with a foreach() to return clean values or arrays.

protected function createVideoNode($vid) {
  $newVideo = Node::create(['type' => 'video']);
  $newVideo->set('title', $vid['title']);
  $newVideo->set('body', $vid['description']);
  $newVideo->set('field_video_id', $vid['id']);
  $newVideo->set('field_thumbnail', $vid['thumbnail_url']);  
  $newVideo->set('field_published_at', $vid['created_time']);       
  $newVideo->enforceIsNew();
  $newVideo->save();
  return true;
}