Now I need to install NVMe (Non-Volatile Memory Express) memory connected using the PCIe to connect to the new SSD form hard drives.

I moved from an ssd 0.500 MB/s (old pc) to an m.2 7000 MB/s (new pc) and the difference I noticed is a lot

The reasons why the ssd is not recognized could be different such as you should check that the port is enabled by the bios.

I found this article about your issue, it is in intalian but you can translate it and it might help you

https://it.easeus.com/data-recovery-solution/m2-non-riconosciuto.html

!discovery 30