I've been successfully building Hercules on a Raspberry Pi 4 (armv8/arm64) for a week or so - first by manually patching the platform macros and then by just picking up the commit that made that patch officially. However, for reasons I can't quite follow (not a C++ person), the compiled servers throw a Bus Error during startup for me. Compiling armv7 executables on armv8 works fine though!