We're heavily using the responsive class field module in a custom project with a Bootstrap 4 theme and Paragraphs. Initial development took place outside of drupal.org's Git repositories. We feel confident to releasing our project's current version as alpha version at drupal.org and hope you'll find it useful in your Drupal site(s) as well.
Added payment methods, autofee to the form payment method and remove card images from the front end of the website. Also updated payment status pending to payment received.