My son is left handed, I taught him to shoot right handed, when he was six years old. It was a similar repetitive exercise like Mickey Mantle’s father did for him. You must either shoot across your face or stop using your dominant eye. To stop using your dominant eye, use and eye patch. When you get used to using left eye with left hand stop using the patch. My son is a world class combat shooter, he has no weak hand. In 6 weeks he will be 50 and just retired as the top shooter in Pararescue.
Training the hand is not really different from training for shooting weak hand in competitive shooting. The object is to shoot into one group with either hand.
You might find that learning to pull the trigger with the middle finger is easier and faster than teaching yourself to use the left hand and left eye. You just lay the first finger on the side of the slide while firing, it will be uncomfortable to start, after the injury. It will take time and practice. For a clip change stand at the foot of your bed, drop the mag onto the bed, practice, practice, practice. Most lefties find a left mag release easier to activate with a left finger tip.
Ed