Lessons learned porting Drupal Media and CKE5 ecosystems

I'd to facilitate a discussion around the lessons I learned through porting the Drupal Media and CKEditor 5 Ecosystems to Backdrop. This will mainly focus on developers and includes topics such as configuration management (converting ctools plugins to config, config performance, return values), changes to entity information, nested modal dialogs, file display fallback support, non-writeable stream wrappers and more. We'll discuss each topic, including what was learned, what was done about it and what improvements can and have already been made to Backdrop core as a result.