“The M1 represents a massive reverse engineering challenge, with lots of bespoke, completely undocumented hardware.”
Apple publishes no documentation for the M1’s hardware. So the Asahi team wrote a hypervisor that runs unmodified macOS and logs every hardware access its drivers make. Disassembling Apple’s drivers directly would risk the project’s copyright status. Apple sells you the machine and leaves outsiders to work out how it actually works.