selected-date-range
There are 2 repositories under selected-date-range topic.
SyncfusionExamples/start-and-end-date-of-selected-date-range-in-flutter-date-range-picker
How to get the start and end date of the selected range in the Flutter date range picker (SfDateRangePicker)
SyncfusionExamples/select-all-days-of-header-flutter-date-range-picker
How to select all days when clicking on the day header in the Flutter date range picker (SfDateRangePicker)