The script has been tested on debian/sid
sudo ./mkimg-unmatched-debian.shUser: debian
passwd: debian
This script ultimately generates a rootfs for nvme. Of course you can also modify it slightly to generate a rootfs for sd.
From Installing Debian on HiFive, if you boot from SD card, you need flash bootloader into sd also.
The bootloader image you can download and to flash it into sd card.