Using current binutils, attempting to build shim eventually results in the following failure:
objcopy -D -j .text -j .sdata -j .data -j .data.ident \ -j .dynamic -j .rodata -j .rel* \ -j .rela* -j .dyn -j .reloc -j .eh_frame \ -j .vendor_cert -j .sbat -j .sbatlevel \ --target efi-app-riscv64 shimriscv64.so shimriscv64.efi objcopy: shimriscv64.so: invalid bfd target make: *** [Makefile:269: shimriscv64.efi] Error 1
There are upstream fixes for this that can be backported to RHEL.