I bought the BMW system. I found that we hardly ever use it as it protrudes too far from the seat back and makes getting in and out of the car way too difficult w/o constantly moving front seats forward just for entry/exit, especially by the middle seat kids. Even in the photos of the the BMW factory rear seat entertainment system (RSE) you can see the screen is attached flat to the front seat back to not hinder entry/exit.
We ended up using a couple of $20 seat back iPad holders from Amazon that are low profile, adjustable and keep the tablet/phones closer than the BMW system to the front seat back. It works with 2 car seats and three kids in the back seat for easy entry/exit. They are a bit flimsy but have not broken yet and its been almost a year since purchase.
https://www.amazon.com/gp/product/B07Q4RHHSL