Currently compiled hsdis-riscv64.so binary complains:

hsdis: bad native mach=architecture not set in Makefile!; please port hsdis to this platform

It seems to be as simple as point to the right BFD arch:
https://github.com/riscv-collab/riscv-binutils-gdb/blob/riscv-binutils-2.37/bfd/cpu-riscv.c#L98