One interpretation would be Many Worlds; that is, every quantum possibility is real in its own multiversal branch. So, to assign moral agency you would need to show that I chose the world I’m in now, over some other version of my life in which different choices were made. Although, I’m not certain you even need to go that far: I have no idea to what degree quantum randomness can actually affect our choices. But, in any case, that too would be out of our control.