I guess the driver was the one that runs on Mac that they were able to refer to? Not sure you have any links to blog posts about this process it sounds so cool

From https://news.ycombinator.com/item?id=39385382 Here's Hector Martin (marcan) talking about their tooling: https://asahilinux.org/2021/08/progress-report-august-2021/

Running macOS in a hypervisor controlled from a second machine (proxy mode + verbose==on) to watch drivers talk to the hardware:

https://asahilinux.org/docs/sw/m1n1-user-guide/#running-a-ma...