Vast majority of hardware used by the open source community is proprietary and undocumented, and always has been. They embrace the challenge of reverse-engineering.
I hope I get to be a badass challenge-embracing reverse engineer like the people behind Asahi one day. I've done some USB stuff but have no idea how they're tackling all the other hardware.
GNU / Linux and BSD would never have started with that attitude. Most hardware was proprietary back in the day, and still is proprietary today. Even Thinkpads (a favourite among BSD devs) have proprietary subsystems that are reverse engineered. The alternative would have been to sulk and whine about it and do nothing. The hardware vendors truly do not give a f**k. They are run by business people, not open source idealists.