Idea Summary
Currently the Oracle JET Datepicker in APEX doesn't allow a developer to set the first day of the week (either declaratively or via JavaScript). An option in the component settings to select Sunday or Monday (or even any arbitrary day) as the first day of the week would be preferable.

Use Case
When building applications that are used in multiple territories, having the NLS settings of the application determine how the datepicker is presented is sometimes not desirable. As the ISO week standard defines monday as the first day of the week, it would sometimes be preffered to adhere to this standard instead of language preferences.