(Glue-2002) Q: How can we use HANA views (calculation views, CDS views) as a source for the extraction?

Yes, you can use all kinds of database and HANA views as a base for the data extraction. The only prerequisite for this is that the view is available through the SAP ABAP Dictionary (transaction code SE11). You can import CDS views or HANA views of all kinds into the ABAP dictionary through the HANA studio by creating an ABAP dictionary object based on your view.