The DevKit currently created on a Windows AArch64 machine uses the x64 compiler binaries (e.g. cl.exe). This can be inspected by running "dumpbin /headers /out:cl.txt cl.exe" on the compiler in the generated DevKit and inspecting the machine architecture line. It should instead use the native Windows AArch64 compiler binaries, for which dumpbin output should show ARM64 e.g.

FILE HEADER VALUES
            AA64 machine (ARM64)
               6 number of sections
...