With this release, there are several new features that help building your solutions as extensions:
- New virtual tables for Report Data Items and all Page Control fields
- Translating Base App help using AL extensions
- Adding help links with user locale on new created objects
- Field group extensiblity
- Report substitution is possible from extensions
See more here:
https://blogs.msdn.microsoft.com/nav/2018/08/31/developer-preview-august-2018/