Note however Zig actually provides libSystem.tbd stubs out of the box, so you can cross-compile from any OS to macOS too as long as you only depend on libSystem

Note however Zig actually provides libSystem.tbd stubs out of the box, so you can cross-compile from any OS to macOS too as long as you only depend on libSystem (the macOS libc.) If you need the rest of the Apple SDK, then you'd need a sysroot (and face the challenges you described.)