Attempting to roast a full chicken or turkey is not the correct way to use microwaves. You must first remove the bones from the bird, then cut the meat into bite-sized chunks. After using a boning knife for the former operation, I prefer to do the latter operation with some good Japanese kitchen scissors, as it is simpler and faster than with a knife.
If you buy turkey/chicken breasts or thighs without bones, then you have to do only the latter operation and cut them into bite-sized pieces.
Then you can roast the meat pieces in a closed glass vessel, without adding anything to the meat, except salt and spices (i.e. no added water or oil). The microwave oven must be set to a relatively low power and long time, e.g. for turkey meat to 30 minutes @ 440 W and for chicken to less time than that, e.g. 20 to 25 minutes. The exact values depend on the oven and on the amount of cooked meat, but once determined by experiment, they remain valid forever.
The meat cooked like this is practically identical to meat cooked on a covered grill (the kind with indirect heating, through hot air), but it is done faster and without needing any supervision. In my opinion this results in the tastiest meat in comparison with any other cooking method. However, I do not care about a roasted crust on the meat, which is also unhealthy, so I do not use the infrared lamp that the microwave oven has for making such a crust.
Vegetable garnishes, e.g. potatoes, must be cooked at microwaves separate from the meat, as they typically need much less time than meat, usually less than 10 minutes (but higher power). Everything must be mixed into the final dish after cooking, including things like added oil, which should better not be heated at great temperatures.
Even without the constraints of a microwave oven, preparing meat like this makes much more sense than cooking whole birds or fish or whatever. Removing all the bones and any other inedible parts and also cutting the meat into bite-sized pieces before cooking wastes much less time than when everybody must repeat all these operations every time during eating, so I consider that serving whole animals at a meal is just stupid, even if they may look appetizing for some people.