You can refer the partitions table of the image here:
https://wiki.radxa.com/Rockpi4/partitions
For SDcard,
dd if=/path/to/image of=/dev/sdx count=32768
You have a bootable sdcard with bootloader only now.
For USB3 device or NVME device,
dd if=/path/to/image of=/dev/sdx bs=4M
Write the whole image to USB3/NVME device.
Sorry if I’m being slow-witted here, but if I understand this: If I can copy the 5 partition images to my NVMe using the correct offsets then the RockPi will boot from NVMe and I no longer need to boot from a microSD? Thanks in advance for your understanding.
I have installed recalbox with your help, but recalbox is in sd card.
I don’t understand if must execute all 2 command dd or only second.
Sorry for my bad english.
No. You still need the uSD card for the bootloader, because if the bootloader in nvme, ROCK Pi 4 can not boot it.
That would be a great idea I was going to ask if anyone knew of any good quality fast low capacity Micro SD cards and is it possible to get them nowadays.
A small capacity EMMC module much better though and preferable to soldering on a flash rom for SPI boot.
I want one! 
hello. first i want to apologize for my english because is not so good. my problem is next, i want to buy Rock pi and use nvme ssd for operating system… i read a lot forum and see i need for this for start my os i need to put bootloader on sd card, emmc or spi flash, is this correct? Or this is posible exclusively and only whit spi flash? is spi flash is not nacessary which version of rock pi i need to buy, is this version 1.3 or i need 1.4 ( i am looking for buy Rock pi 4 model B 4 gb)? and i can not found tutorial how can i install os on nvme with bootloader on sd card or emmc, i found only installation on/with spi flah and nvme ssd?
thanks for your time and help