System Requirements for SAP Fiori Elements Development with SADL
To use SAP Fiori elements in SAP NetWeaver AS ABAP, the minimum version of SAP NetWeaver is 7.50 SP01, otherwise the SADL will not work.
Many new annotations are added in each upgrade of SAP NetWeaver. Hence, SAP Fiori elements will be more powerful if you choose the newest version of SAP NetWeaver.
In general, CDS works on any database, but SAP HANA is recommended when good performance is needed, due to CDS push down the calculation to the DB layer.
System Requirements for SAP Fiori Elements Development with Local Annotation
When writing annotation as a local file using SAP WebIDE, SAP Fiori elements works with any OData service, even from non-SAP back end.
If SAPUI5 runs on a non-ABAP platform like SAP CP, or you're using OpenUI5, SAP Fiori elements only requires the version of SAPUI5/OpenUI5.
If SAPUI5 runs on ABAP platform, SAP Fiori elements require version of SAP_UI.