I've got a complicated bottom sheet layout design that is different than anything I've done before. 1. The bottom sheet can never go away, there's a minimum amount of UI that should be displayed. 2. When dragged up a bit something should be revealed above that minimum UI. Should stop at this place when doing a small drag. 3. If it keeps getting dragged up then content should come up from below the minimum UI. 4. The UI normally showing behind the bottom sheet should have content relative to the minimum UI portion but not slide up as the sheet goes bigger. The expanded sheet should hide the other UI. Any advice on resources to learn how to do something like this. Do I need to make my own bottom sheet function?

Re 1: There's a bottom sheet layout or whatever that does exactly this. It has a persistent bottom sheet.