Years ago there was a thriving aftermarket for sunroofs but these were generally cheaply made and poorly installed which gave them a bad reputation. There are a few aftermarket sunroof retailers remaining but with most cars/suvs now have unibody construction, adding a sunroof will almost certainly reduce the rigidity of the structure and have negative consequences on handling as well as squeaks/rattles, etc. I can't help but think that it will reduce the value of the vehicle.