When you need to display a set of actions to the user without loosing focus on the current page, a Bottom Sheet might be a good solution for that. Maybe you want your user to confirm an action, like adding a certain amount of items to the cart without showing a new page. Examples of this widget can be seen in both native iOS and Android, either while confirming a purchase via TouchId (or FaceId) in iOS or accepting a purchase to the Google Play Store in Android.
This article by Dane Mackier goes into how we should approach implementing Flutter’s Bottom Sheet Class with all the do’s and don’ts for a good Flutter codebase.
Flutter Beginners Guide to using the Bottom Sheet – Flutter Community – Medium