The deployed application works fine now. But there are still some issues like access with basic authentication, not optimal data reading (getting status for every project in a separate request), lack of OData V4 features for the Project API and so on.
This can be fixed by creating an own service via SAP S/4HANA Cloud Developer Extensibility.
As always the creating of the own service has its pros and cons:
- Tailored API: cleaner and easier to understand/mock
- Better performance (no additional fields, data, views, etc.)
- Lower network overhead (no additional requests)
- Custom business logic is available
- Custom authentication control (OAuth)
- Custom authorization control
- OData V4 if necessary
- ABAP Developer skills are needed
- Lifecycle responsibility