I made the experience more than a year ago that it is not possible with Windows 7, already when installing the Windows 7 operating system, the M.2 SSD or the controller is not recognised, Windows 7 does not have an NVMe driver.
If the SSD or motherboard manufacturer has a Windows 7 driver (so-called floppy driver), then the installation and of course booting should not be a problem.
But in the meantime Microsoft has a solution:
https://support.microsoft.com/en-us...