An oven is a kitchen appliance that heats food through a heating tube.
They have different principles and different heating temperatures.
The microwave oven is more than 100 degrees at most, and the oven is two or three hundred degrees.
If the microwave oven has no barbecue function and the temperature does not go up, the leg of lamb can't be baked at all. If you marinate the leg of lamb and put it in the microwave oven, stew it at most, which is likely to be cooked externally, not barbecued.