So it's been a long journey but I finally got a new system in my E89 premium sound non-iDrive car. BMW sure doesn't make it easy. The previous thread with the Joying radio got the ball rolling. I ordered the harness and adapters from Germany but they didn't work. The Z uses fiber optic cable instead of speaker wire. The Germans then directed me to buy a $250 fiber optic adapter that still didn't work. $420 later I was still going nowhere. Eventually I just decided to scrap the factory amp and got a new JL Audio amp that sounds 100x better.
I decided to go with the Pioneer 3400NEX. It is a flip out unit that fits in the single DIN bay. When flipped out it does obscure the AC controls but there's a button that you push to temporarily flip the screen to access them. You can see it in the video. The steering wheel controls all work except for the AC recirc button. I wish it could be programmed to activate that temporary screen flip button. CarPlay works flawlessly and the backup camera is very helpful. I initially wanted to get the Alpine Halo but the fit just wouldn't work well do to the size. So far I'm very happy with the setup.
https://www.youtube.com/embed/K4usy6G7sog