The following works using an Intel 760p M.2 NVMe...
Download Radxa Debian 9 Desktop image:
https://wiki.radxa.com/Rockpi4/downloads
Find the device letter for your SD card and write the image to it:
sudo fdisk -l
gzip --stdout rockpi4-debian-stretch-desktop-arm64-20190730_2022-gpt.img.gz | sudo dd of=/dev/sdx status=progress
Boot Rock Pi 4 with Radxa Debian 9 Desktop SD Card:
<Open a command-line window such as LXTerminal>
sudo su - root
apt-get update && apt-get -y dist-upgrade
<This updates the Radxa tools and asks (type "y") to write the latest uboot image to the /dev/mtd0 SPI chip>
Download and write the Armbian image to the NVMe drive:
wget https://dl.armbian.com/rockpi-4b/archive/Armbian_20.02.1_Rockpi-4b_bionic_current_5.4.20_minimal.7z
apt-get install p7zip-full
7z e -so Armbian_20.02.1_Rockpi-4b_bionic_current_5.4.20_minimal.7z | dd of=/dev/nvme0n1 status=progress
Add two lines to the armbianEnv.txt file:
mount /dev/nvme0n1p1 /mnt
vi /mnt/boot/armbianEnv.txt
fdtfile=rockchip/rk3399-rock-pi-4.dtb
overlays=pcie-gen2
Power off the Rock Pi 4 and remove the SD Card.
Power on and it boots Armbian using the NVMe drive.
FYI... You may have to jumper pin 23 (SPI_CLK) and 25 (GND) which disables the SPI chip to boot Armbian from an SD Card. You could also boot the Radxa Debian 9 Desktop and run /usr/sbin/flash_erase to wipe the SPI chip.
