I'd want to make sure the installation doesn't cut into any structural members in the roof of the car. I just went out to my car and ran my hand across the roof liner. While it's not real obvious visually, there is a bump which runs between both B pillars. I'm betting this is a reinforcement piece that is part of the structure of the car. With the amount of space required to have a decent sun roof put in, I don't see how one can be installed without cutting into this area. Also, I would wonder how much this would affect loading on the roof. If you have plans on installing a roof rack, I would think twice about putting in a sun roof.
The other consideration is water drainage. Cars designed to have sun roofs from the factory have drainage channels built in to allow the inevitable water penetration in the sun roof to drain safely away. I don't know how an aftermarket kit would deal with this if at all.
2019 Toyota C-HR LE Silver Knockout Metallic
2013 BMW 135i Carbon Black
2009 Ducati 848 Pearl White/Black
2004 Kawasaki Ninja ZX-10R Black