Chaser
Thus my view that:- The small amount of debris (and its condition) recovered is suggestive of ejection (likely at high altitude and high speed) without high speed destructive impact with a solid surface such as other aircraft structures and/or the surface/water
I wouldn't argue FOR a high-speed impact. But you might also consider that this debris could have resulted from airframe subsections breaking upon impact at less than a high speed. Keep in mind we have no clue the condition of debris which sank.
If the aircraft largley disintegrated at altitude I would think many more floating items would be found.