Just to point out that many cheaper M.2 SSDs on offer aren’t NVme but are in fact NAND and may not be compatible … and even if they work they are still considerably slower. The same for M.2 slots on a mainboard - if NVme isn’t specified then be wary.
Performancewise for Windows and MSFS a 500GB NVme is plenty if you then use a normal SSD for your packages, only in sim menu to flight loading times should be affected and still way better than HDD.