[cgio]

If you put ETL and ELT in the same layer you have missed the essence of data platform architecture schools in the last few years. DW is ETL. Data lake is ELT. Then you mix and match (e.g. lakehouse etc.) The distinction between transformation post or ante ingestion is the major thing to drill into. The next one to master is streaming versus batch and after those you start hitting interesting problems like orchestration, snapshots and consistency layers. Not too complex a domain, but it requires some practical requirements to have to find these things out.