Where can I find Mojave Kernel Headers?
Apparently XCode command line tools doesn't install the headers by default anymore. However, it does provide a package in /Library/Developer/CommandLineTools/Packages. On my system it was /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg. I installed this package and then the headers showed up in /System/Library/Frameworks/Kernel.framework/Headers.