Installed using:
sudo pacman -S riscv64-elf-binutils riscv64-elf-newlib riscv64-linux-gnu-gcc yay -S riscv64-unknown-elf-gcc riscv64-unknown-elf-binutils riscv64-unknown-elf-picolibc yay -S riscv-pk-git # which has a broken repo path, you need to manually edit PKGBUILD
then, run using: spike /usr/riscv64-linux-gnu/bin/pk ex1.riscv