The kernel tree was already shared; pre-M1 releases of the XNU kernel for Intel macOS already had (only partially censored) support for Ax line CPUs on iOS devi

The kernel tree was already shared; pre-M1 releases of the XNU kernel for Intel macOS already had (only partially censored) support for Ax line CPUs on iOS devices :) You can build a completely open source XNU kernel core for M1 and boot it, and iterate kernel drivers, yes. All of that is fully supported, they have the KDKs, everything. It's been self hosted since release (well, things were a bit rocky the first month or two in the public version as far as custom kernels).