The Windows platform doesn't run the APE shell script which checks $(uname -m). I don't know yet if it's possible to have a fat portable executable. I would hope that it's possible. I may be mistaken but I vaguely seem to recall reading about portable executables that existed a long time ago that had multiple optional headers for both Windows and OS/2. It would be nice if Microsoft did, or could, make that possible today, so we can have arm64+amd64 pe binaries. Until then, we need to rely on Microsoft's excellent x86-64 emulation support.