you can apply the ETL process at the same way you usually do through QlikView: you should create a set of apps in which you can insert the Qlik Scripts in order to do your ETLs.
You can also apply the Qlik Deployment Framework (QDF) the same way as QlikView (obviously you should change direct connections to lib://... connection flavour).
TSEEQ, The Structured ETL Engine for Qlik, might be useful for your project. TSEEQ is an ETL engine rather than a process; TSEEQ can be used to streamline whatever ETL process you use in your Qlik Sense implementation.
For more information, please see https://tseeq.net/
Jeff R. Robbins