itsme

To install Armbian, use the standard armbian-config menu, there is everything you need for easy installation of the system on NVMe.

It looks like you didn't understand my answer. I will explain in detail. There are several options for working with NVMe. 1. Starting the system + u-boot completely immediately from NVMe (this option is not known to me on RK). 2. Placing the u-boot on an intermediate medium (SPI\SD\eMMC\USB) and placing the entire system completely on NVMe. This is the simplest and most common way to use the entire NVMe system use SPI.  3. Placing the u-boot and boot partition with the kernel on intermediate media, and placing the system on NVMe. I repeat, u-boot is placed on Station P2\M2 on eMMC and the /boot partition can be placed, during normal operation of the system it is used only during boot and works mainly in read-only mode, it is not used in the rest of the system. The working system uses only NVMe and, accordingly, the speed of the system is determined by the speed of NVMe only. This option works well on all Station M1\M2\P1\P2.
 
My equipment is in heavy use right now, try asking other owners to run your tests.