The name gives it away; It's a widget that automatically checks your content pages on the website for some points. (Which points? We'll be happy to tell you below.) Automatically? Yes! Authors don't have to be trained or reminded to do a "check." It just happens "on the fly."
We use a contributed module, Editoria11y Accessibility Checker (https://www.drupal.org/project/editoria11y), which can be assigned to certain roles and/or users for this purpose. https://www.youtube.com/watch?v=YXhmj_Gt6dM
Created specifically for authors, the widget focuses on the content of the page and not on the underlying code (or Drupal theme notifications). The widget is therefore perfectly suitable as an additional addition but not a replacement for a WCAG Scan.