in Flutter/Dart, is there a way of creating a List that has list items of varying height and starts from a specified item

Question

I am implementing a list that builds its children lazily. This list has items of varying sizes and also needs to start from a specified list item (as opposed to starting from the first or last items). The list is on a tab which is one of a few tabs in a TabBarView. The TabBarView itself is the body of a NestedScrollView. My list should expand and collapse the SliverAppBar as it scrolls.

I have used the ExtendedNestedScrollView package since i also need to maintain the current scroll position of each tab together with the ScrollablePositioneList package to set an initailScrollIndex the item my list should start from. Objectives

1. List starts from specified item ✅
2. List expands and collapses SliverAppBar when scrolled (currently using the NotificationListener to expand and collapse the SliverAppBar manually)
3. List maintains scroll position when switching between tabs ❌