How can I set a custom form's element after a managed_file ajax callback?

Question

Scenario:

I have a custom form whose first step is to upload a file using a managed_file field element.

Then, after this manged file is uploaded I want to rebuild the form using information from the managed file and display new form elements that should only exist after the managed file is uploaded.

I have struggled with this for days and cannot get a working solution. The first problem is that the managed_file already has an ajax callback so I can't seem to add my own to populate and/or return field elements after the file is successfully uploaded.

I've gone as far as overriding the managed_file type with a custom form field type but I can't seem to be able to return actual form elements AND an ajax response (one of the other). Code example of my override below.

In short, how can I repopulate a custom field after a managed file uploaded is completed and add new fields dependent on the file that was uploaded?

/**
 * My Managed File Element.
 *
 * @FormElement("my_managed_file")
 */
class MyManagedFile extends ManagedFile {

  /**
   * {@inheritdoc}
   */
  public static function uploadAjaxCallback(&$form, FormStateInterface &$form_state, Request $request) {


    $response = parent::uploadAjaxCallback($form, $form_state, $request);    
    
    return $response;

  }

}