Oliver Kreylos recently posted a detailed video about throwing physics in VR: https://www.youtube.com/watch?v=eREYrwCwqYo

The key points are that it's important to use the controller's linear and angular velocities (now available, cf. issue #619 and the corresponding fields in XRPose), and that the calculation should use a cross product of the angular velocity with the vector from the controller's IMU position to the object's center of gravity.

If I'm understanding it right, gripSpace is the pose that should be used to render virtual objects such that they appear to be held in the user’s hand which isn't necessarily equivalent to the IMU position.

Would it be appropriate to expose an imuSpace, or equivalently a static offset between gripSpace and imuSpace? This could potentially also be done as part of the input profiles library since it's a fixed property of the controller.