I’ve tried the flutter_physics today and was quite pleasantly surprised. It has variety of different and opinionated physics modes and curves, but is quite powerful at the same time. A simple animated widget becomes much more organic thanks to that.
Maybe few more thoughts from me.
A technique that I’m often using is to create my custom animation controller by passing the vsync to a ChangeNotifier. This way I can orchestrate my animations manually, do any calculations I need by hand and just notify the builder about new frames. You can see example of that in my old codepens (e.g. TrexGame class here or Boids simulation).