The MacOS SDK devkit does not include some files needed
for building the new 2D metal rendering pipeline, so our
project lanai build is currently only able to be built with
local tools.

Specifically this folder exists in the devkit
Xcode.app/Contents/Developer/Platforms/MacOSX.platform/
but the subdirectory "usr" is missing, ie :
Xcode.app/Contents/Developer/Platforms/MacOSX.platform/usr

We minimally need the tools "metal" and "metallib but
probably almost everything (in lib and bin etc) is going to
be necessary to run these and it looks like it will add about
36Mb to the devkit installed footprint.

Can you please add that tree ?