We need the ABAP’er to understand the core concepts of S/4HANA and include the following key competencies, such are:

1. Experience with Core Data Services (CDS) views for defining data modeling, associations, and UI annotations.
2. Experience with AMDP (ABAP Managed database procedure) for leveraging database-specific code for heavy, code-to-data, HANA-optimized logic and BRFplus (Business Rule Framework plus) for business logic, and BTP for extensions, while utilizing BTEs for legacy integrations.
3. Experience with RESTful ABAP Programming Model (RAP): The modern standard for building SAP-native, cloud-ready applications.
4. Experience with OData Services: Creating data services for backend data to be exposed for UI/Fiori consumption.  
5. Demonstrate knowledge of Fiori elements and Fiori launchpad configuration for setting up apps, tiles and catalogs.
6. Demonstrate knowledge of SAP Clean core i.e., to build custom extensions without modifying standard SAP code (Side-by-side, Key User, Developer Extensibility)
7. Demonstrate knowledge of HANA Optimization: Replacing traditional code with faster, code-pushdown techniques

We DO NOT need:

1. SAPUI5:We are not looking to build web-based or mobile-first applications. We don’t need any Fiori Front end or UX Developer.
2. Javascript/CSS or HTML: We are not looking to customize any Fiori UI

I believe ABAP’er who worked on S/4HANA for last 4 years consistently in 1 customer would have experienced all the above 7 points.