If your M.2 is an NVMe drive, you will not find it listed by name along side the other drives in your system because it is not a SATA device. It is a PCIe device and generally only visible by name as a configurable hardware device inside of the BIOS with RAID enabled. If you are using AHCI, you may find BIOS settings for it (like 2X or 4X mode) but not the device itself by name. Likewise, you generally don't see your other PCIe devices like WiFi, NIC or GPU enumerated and identified by name in the BIOS.
// EVGA Z690 Dark K|NGP|N | 13900K | RTX 4090 Suprim | 32GB DDR5 Hynix A-DIE @8200 | SuperNOVA 1600 P2 | HC-500A Chiller | MO-RA3 360 || DG-86Banshee
// ROG Z690 Apex | 13900KF | RTX 3090 K|INGP|N | 32GB DDR5 Hynix A-DIE @ 6800 | Corsair RM122x SHIFT | XT-45 NOVA || 5000D AirflowHalf-Breed
// Precision 17 7720 | 7920HQ (BGA filth) | Quadro P5000 16GB (MXM) | 32GB DDR4 || Grade A Off-Lease Refurb