Add print button in the "Review order" page
You can try using the PrintFriendly &amp; PDF module, which has a version for Drupal 7 and one for Drupal 8. (The development snapshot for Drupal 8 has been created on July 27, 2017.)

The description of the module says:


  The #1 Print and PDF button for your Drupal site. Printer Friendly
  pages without coding, css, or print.css. Fast, easy, and professional.
  
  The Print Friendly &amp; PDF button saves paper and ink when printing or
  creating a PDF. It's fast, easy, and looks great when printed. Add the
  button now, and your users will see the difference.


Using this module you can add a print button to review order pages.