Hi, curious, why did You choose to look for ways to mount tablet for Apple Carplay, instead of getting a retrofit, which uses Your factory MMI screen and looks a lot cleaner?
This is one of examples:
"Wireless Apple CarPlay Android Auto retrofit kit Audi A1 2010-2018 - Unique Auto Developments"
https://unique-ad.co.uk/product/audi-a1-carplay-retrofit-kit-installation-available/
Audi A4 B9 3.0 TDi quattro 200 kw