I have it installed already bud, so thanks. Not sure what I need to study to answer that one tiny question. Anyway, I bet my question was not formatted correctly. So let me try again, it's very late here and I am very tired.
I am new at UEFI installs, and my system is a UEFI based system, obviously. I have never seen this /boot/efi creation before, obviously, and I have been installing Linux distros longer than I can remember, well almost. I have used Linux on and off for roughly 20+ years, or ever since the mid to late 90's. But before now (now as in this last summer) I was always using a Intel x58 based system, which is legacy BIOS (so were all the machines before then) and I have installed linux hundreds of times on legacy bios systems. I didn't know that I would need to re-read tons of material just to install it on this new system, but maybe I should anyway, I guess.
Therefor, the ONLY part I was confused about was the missing d. step above. (as I am suggesting below)
8. Select the unpartitioned space → Create
a. Size → Use remaining
b. Filesystem → select ext4
c. Mountpoint → select / (root) → OK
d. Select the location for the bootloader, normally the MBR device, in this case "/dev/nvme0n1" for the bootloader.
d. was missing and since this is a UEFI install and I created this /boot/efi per the guide, which is new to me, and I thought that maybe this bootloader location was not needed, or needed to be changed from the default to something else, like the /boot/efi maybe, etc (again I assumed this was for the bootloader location already). If one is to just ignore that option in the manual installation, then at least a "d. Ignore the bootloader location and let it stay on the default option" would have been helpful, or simply "d. Ignore all other options on this page".
I already know how to use Manjaro (amongst many others), just not exactly how to install onto my NVMe device on a UEFI system (I was thinking the process was slightly different, which is why I am in this thread now). So please point me to any reading material you think I should look at, because all the links I was already pointed to I have already read years ago and many many times. I don't believe any of them would answer this question "does the bootloader location change when installing on a UEFI system and manually creating the /boot/efi partition". I somehow doubt that would be answered.
Oh and just ignore my first Grub Bootloader question above, I simply forgot about all the new kernels I might be installing in the future, which obviously Grub is needed for. That was a big DUH on my part, sorry.
Anyway thanks man, Manjaro is installed and running great so far, and without the question answered. Tested Windows 10 and it too is still running great. Happy to finally be back in this fine OS. Oh, and earlier this year I FINALLY got my uncle to leave Mint (he was a mint user for like 10 years now I think) and he is blown away by Manjaro... Today he told me he will never be going back to Ubuntu based distros, lol. Good for him...