Hi,
First: Thanks 
Using the instructions from the first post, I successfully installed NvmExpressDxe_5.ffs into the BIOS of my ASUS UX501JW and now I’m using it again with NVMe drive. Many thanks for the manual, because this model only supports “PCIe AHCI” drives, and without mods, I couldn’t install the system anymore - the original M.2 drive was broken.
OK. But I am writing because the following few words may be useful to someone (but maybe someone wrote it before in more than 7k above posts …):
Even with a modified BIOS, I still had a problem: I couldn’t install Windows 10 21H2 because in UEFI mode the installation got stuck when changing the graphics mode (probably the source of the problem was the Intel UHD + GTX 960M tandem). So the situation was as follows: the disk was seen in the BIOS, but it was not possible to install Windows in MBR mode (there was information about the inability to boot the system in this mode) and in UEFI mode the installer crashed. But I saw before that the disk is visible by Macrium Reflect run from Rescue Media.
So I made the following procedure (a little workaround): I’ve made Windows 10 machine in VirtualBox with EFI enabled. Then I started Windows 10 install from ISO. Before the first restart I turned off the machine. Next I made the image of virtual disk (GPT one was created) using Macrium Reflect. And I restored it to my laptop. And … the laptop successfully booted into the Windows 10 installer, the installation of which continued. Now everything works great
Regards,
Marcin