Refactor field configuration to use \Drupal\Core\Entity\EntityDisplayBase
Current implemention of compose is using field layout with some hacks. Field layout will be removed in 8.7, with the features we want moved into other core classes.
See https://www.drupal.org/project/drupal/issues/3007167 and https://www.drupal.org/project/drupal/issues/2844302
Ensure field_group still works
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information