WOW, much basic, but not intuitive in the slightest.

Trying to install Win 10 Pro to M.2 drive. System/MB supports the OS, but noting the difference in steps whether the M.2 drive is seen in BIOS, boot is on UEFI/Legacy/Both, and the NVMe Firmware Source setting for SMC systems.

BIOS Optimized defaults

Non-UEFI USB Boot Media installation - selecting M.2 drive to install Win10 Pro

Stops here.

UEFI USB Boot Media installation - selecting M.2 drive to install Win10 Pro

Works.

After it finishes installation, it warns that it is automatically rebooting. Windows Boot Manager and the M.2/NVMe drive shows up at the top of Boot priority.

On default settings, it will not list the M.2/NVMe drive as a bootable disk, but it will be seen in the Win10 Pro installer. After installing, it will show up as 'Windows Boot Manager' with the full part number of the M.2/NVMe drive.

After selecting the Windows Boot Manager right after the Win10 Pro installation rebooted the system, it will run a disk check and repair that will look like below screen.

This takes about 3-4 minutes, and will reboot once more. Without interrupting system boot to visit BIOS Menu, it will boot straight into Windows 10 Pro Basics and Welcome screens.

Language, Keyboard Layout (Skip). It did not list any available Network ports, so I used 'I don't have internet'.

After Account, Password, and declining all services, it will take seconds to finally bring me to a desktop.

Welcome to Windows 10

Missing Drivers

There are no drivers, or network. Since no network, you cannot have Windows 10 search and auto-update to fill in the drivers needed for installed hardware. Price for one's UI preference, or whatever some are more comfortable with, or will not take the additional time to learn Linux, or why Linux is used in >90% of supercomputers.

Good thing about Linux right after fresh installation is that the onboard network ports are already seen, and can work if I enabled them through Linux OS installer, or even in the settings without updating the OS at all. I could also query the installed hardware without drivers.

With Windows, It cannot fully detect installed hardware from a fresh installation, so I have to yet again plug a USB into another computer- this time to load drivers onto it, and then plug that USB to spoonfeed this Windows 10 Pro

Windows 10 drivers are limited on servers, and heavily varies from manufacturer to manufacturer on their respective resource page from their websites.

Obtaining drivers for remaining hardware

1. Visit your system motherboard website's driver page
2. Filter the drivers for Windows 10
3. Locate and download chipset drivers
4. Locate and download network drivers
5. Load both drivers' .zip files onto USB drive, then unpack them
6. Plug USB into your Win10 Pro system, first install Chipset drivers using the 'application' file
7. Restart system
8. Install Network drivers using the 'application' file
9. Once network drivers are installed, connect to a network
10. Scan for Windows Update, reboot system after every completed batch of updates; repeat if necessary until Win10 system is up-to-date

Example

1. My system is an Exxact <whatever nomenclature at the time> that uses a Supermicro SYS-7049GP-TRT. Supermicro's website is here, and I click on their Drivers & Utilities link below the system image.
   

2. Filter and download drivers for chipset and LAN for Windows 10, then download both

   
   

3. Unpack both zip files onto a USB drive

   WinRAR is free to download, in case you do not have a package utility in Windows. Personal choice, but I deleted the .zip files, since it is not needed after extracting them.

   
   

4. Plug USB drive containing the Drivers onto the newly installed Win10 Pro system, install Chipset drivers first

   
   

5. Reboot system when it asks after the Chipset driver installation - VERY IMPORTANT TO DO BEFORE INSTALLING NETWORK DRIVERS
   

6. Install Network drivers

   
   

7. Check for Windows Updates, reboot as necessary