Thanks, that did work.
I actually did use the option in the dietpi config to flash the SPI.
At first, I tried installing u-boot from their GitHub repository and follow the commands written there, but when I tried make rock-5b_defconfig I got the error -bash: make: command not found despite me using cd u-boot before. So before creating this issue, I looked for other threads with a similar problem and stumbled onto this article, with this solution:
Orange Pi 5 systems will get a kernel and U-Boot update with next DietPi update, which should also enable NVMe support, after flashing the new bootloader binary to SPI via dietpi-config > Advanced Settings > Update SPI bootloader: Orange Pi 5/ROCK 5B | Kernel update and migration by MichaIng · Pull Request #6532 · MichaIng/DietPi · GitHub
So I tried it, but that wasn’t enough to get NVMe boot to work, so I created this issue.
I’m not sure if the SPI flash is necessary after editing /boot/dietpiEnv.txt & /boot/boot.cmd and recompiling boot.cmd & boot.src with mkimage -C none -A arm64 -T script -d /boot/boot.cmd /boot/boot.scr or wether my first flash was enough. This time I also used the option above and flashed the bootloader to the storage device which was the nvme. Not sure if that’s necessary but it can’t hurt.