I don't know if this problem is specific to ARM64 or RISCV64, I just happen to have ARM64 and RISCV64 Ubuntu-VMs:
lars@ubuntu-arm64-QEMU-Virtual-Machine:~$ uname -a
Linux ubuntu-arm64-QEMU-Virtual-Machine 7.0.0-28-generic #28~24.04.1-Ubuntu SMP
PREEMPT_DYNAMIC Wed Jul 1 15:37:52 UTC 2 aarch64 aarch64 aarch64 GNU/Linux
lars@ubuntu-arm64-QEMU-Virtual-Machine:~$
-o obj/GormObjCHeaderParser.obj/ParserFunctions.m.o
clang -shared -Wl,-soname,libGormObjCHeaderParser.so.0 -pthread -fexceptions -rdynamic -o ./obj/libGormObjCHeaderParser.so.0.0.1 obj/GormObjCHeaderParser.obj/NSScanner+OCHeaderParser.m.o obj/GormObjCHeaderParser.obj/OCClass.m.o obj/GormObjCHeaderParser.obj/OCHeaderParser.m.o obj/GormObjCHeaderParser.obj/OCIVar.m.o obj/GormObjCHeaderParser.obj/OCIVarDecl.m.o obj/GormObjCHeaderParser.obj/OCMethod.m.o obj/GormObjCHeaderParser.obj/OCProperty.m.o obj/GormObjCHeaderParser.obj/ParserFunctions.m.o -L/home/lars/GNUstep/Library/Libraries -L/usr/GNUstep/Local/Library/Libraries -L/usr/GNUstep/System/Library/Libraries -lgnustep-gui -lgnustep-base && (cd ./obj; rm -f libGormObjCHeaderParser.so; if [ "libGormObjCHeaderParser.so.0" != "libGormObjCHeaderParser.so.0.0.1" ]; then rm -f libGormObjCHeaderParser.so.0; ln -s libGormObjCHeaderParser.so.0.0.1 libGormObjCHeaderParser.so.0; fi; ln -s libGormObjCHeaderParser.so.0 libGormObjCHeaderParser.so; )
gmake[1]: Leaving directory '/home/lars/Development/gnustep/apps-gorm/GormObjCHeaderParser'
Making all in GormCore ...
gmake[1]: Entering directory '/home/lars/Development/gnustep/apps-gorm/GormCore'
Making build-headers for framework GormCore...
/usr/GNUstep/System/Library/Makefiles/mkinstalldirs GormCore.framework/Versions/0/Headers
/usr/bin/install -c -p -m 644 GormCore.h GormCore.framework/Versions/0/Headers/GormCore.h
/usr/bin/install -c -p -m 644 GormBindingsAbstractInspector.h GormCore.framework/Versions/0/Headers/GormBindingsAbstractInspector.h
Generating GormVersion.h from Version file...
/usr/bin/install -c -p -m 644 GormVersion.h GormCore.framework/Versions/0/Headers/GormVersion.h
/usr/bin/install -c -p -m 644 GormAbstractDelegate.h GormCore.framework/Versions/0/Headers/GormAbstractDelegate.h
/usr/bin/install -c -p -m 644 GormBoxEditor.h GormCore.framework/Versions/0/Headers/GormBoxEditor.h
/usr/bin/install -c -p -m 644 GormClassEditor.h GormCore.framework/Versions/0/Headers/GormClassEditor.h
/usr/bin/install -c -p -m 644 GormClassInspector.h GormCore.framework/Versions/0/Headers/GormClassInspector.h
/usr/bin/install -c -p -m 644 GormClassManager.h GormCore.framework/Versions/0/Headers/GormClassManager.h
/usr/bin/install -c -p -m 644 GormClassPanelController.h GormCore.framework/Versions/0/Headers/GormClassPanelController.h
gmake[2]: *** No rule to make target 'GormCore.framework/Versions/0/Headers/GormCodeExporter.h', needed by 'internal-framework-build-headers'. Stop.
gmake[1]: *** [/usr/GNUstep/System/Library/Makefiles/Master/rules.make:297: GormCore.build-headers.framework.variables] Error 2
gmake[1]: Leaving directory '/home/lars/Development/gnustep/apps-gorm/GormCore'
make: *** [/usr/GNUstep/System/Library/Makefiles/Master/serial-subdirectories.make:53:
internal-all] Error 2
lars@ubuntu-arm64-QEMU-Virtual-Machine:~/Development/gnustep/apps-gorm$
I don't know if this problem is specific to ARM64 or RISCV64, I just happen to have ARM64 and RISCV64 Ubuntu-VMs: