This is a continuation of #32748, since it's preferable to have the complete list of to-dos for Android Q as its own issue rather than as part of a comment thread.

These are the different tasks that need to be completed to help myself keep track of progress and what else needs to be done. This will also help if I missed anything:

• Expose insets.systemGestureInsets on MediaQuery.of(context).systemGestureInsets
  Done with Add MediaQuery.systemGestureInsets to support Android Q #37416 - This allows developers to place draggable widgets outside of the system gesture insets
• Expose setSystemGestureExclusionRects API
  This allows developers to change remove gestures from non-mandatory insets. After exposing the API to the framework, the next step would be to create a convenience widget that sends wraps itself in the exclusion rect. See Expose Android setSystemGestureExclusionRects and getSystemGestureExclusionRects #54397
• Expose getSystemGestureExclusionRects API
  Conversely, it would be good to have a way to query what system gesture exclusion rects have been set. See Expose Android setSystemGestureExclusionRects and getSystemGestureExclusionRects #54397
• Android 10 not building on a physical device - see Flutter on Android 10 (API level 29) issues #39827 for more details
• New Android 10 activities transition - see [Android 10] New transition when opening new activities #39812 for more details

Edit: We don't plan to expose an API for mandatory system gesture insets, since they are a subset of the complete system gesture insets. Developers using system exclusion rects should follow a request to setSystemGestureExclusionRects() with getSystemGestureExclusionRects() and work with whatever exclusion rects the system granted, rather than assuming that the request was met.