I have performed a similar up grade today.
MSFS was installed originally on a spinning rust disk (F:).
I then moved my steam directory to my SSD drive (D:), this didn’t go to plan as it was the same time as the lsat update and had to re-download the whole thing again…
After this I bought another NVME drive, prior to installing I renamed the D drive to A. Restarted and installed the new M2 drive, formatted as D.
I then copied the steam and MSFS directories to the new drive (now D) and launched the sim. No issues and loads a fair bit quicker now…
Happy!