I really hope WireGuard becomes a standard and get's included in the macOS/iOS and Windows kernels as well. Key management and and other fancy features could be left to userspace applications but having the basic wg capability in the kernel would be great.
Seems like a very long shot to make it into Apple products both because of the license and the fact it wasn’t invented in Cupertino.
FWIW the userspace implementations are quite good, and still out performs IPSec.
I don't think there license would be a problem, as it's GPLv2, not v3.
But the 'not invented here' syndrome is very real.
Boringtun is bsd licensed. clean room implementations and all that...