I could understand Apple not wanting to jump all over Ryzen 1000 from day one, but not even Zen2 2-based Ryzen 3000? Even after the whole 5G spat it had with Intel?
The thought would be that they don't want to do any architecture shifts before they bring it all over to their own ARM chips. And AMD still doesn't really deal with laptop processors.
Firstly it might be more complicated than that, they may have a contract in place with intel where they need to stick with them for X amount of years in return for cheaper stock or better deals elsewhere (Apple and intel work together on other things). That’s hypothetical, but it’s certainly not as simple as “they should just switch”.
Secondly Apple might be waiting for their own chips to reach a point where they can be used in their laptops/desktops and jump on to that. It would be overkill to use ryzen as an interim.
Some x470 boards support it to via an addin card and thunderbolt header. To get displayport passed through you need to run a cable from your graphics card output to the addin card input. It's not very tidy and doesn't work 100%.
I'm hoping someone eventually just does the needful and sticks a thunderbolt chipset on a PCIE4 graphics card and makes it work somehow.
I'm not sure what they're waiting for exactly.