How to programmatically import a feed?
This is working for me. Note: You will need to know the numerical $id of your Feed from the D8 DB table feeds_feed. In my case it is 1 so $id = 1.

use Drupal\feeds\Entity\Feed;

function mymodule_cron() {

  /**
   * Runs single feeds on cron
   */

  $feed = Feed::load($id);
  if (!$feed-&gt;isLocked()) {
    $queue = \Drupal::queue('feeds_feed_import:' . $feed-&gt;bundle());
    if ($queue-&gt;createItem($feed)) {
      // Add timestamp to avoid queueing item more than once.
      $feed-&gt;setQueuedTime(REQUEST_TIME);
      $feed-&gt;save();
    }
  }
}