As far as I understand, that the API Products are Drupal entities, which extends DrupalEntityControllerInterface.
Is there a way to,
1. Attach custom Drupal Fields to the API Products? (Using Fieldable property in entity creation).
2. Integrate API Products with Drupal Views. (Eg. Using hook_views_data or creating Entity Reference Views)
Is there any custom module available which supports this already?