So not sure this is even technically possible, but is it possible to have a PCIe x8 slot card that has 2 NVMe slots and each are available in the UEFI/OS as separate drives? I think I've seen some ...

This M.2 allows for devices from 2242 to 22110 in both SATA and PCIe mode, with the latter supporting PCIe 3.0 x4 drives in AHCI or NVMe modes.

Kioxia and Xinnor have collaborated to deliver a high performance PCIe 5.0 NVMe SSD RAID solution for enterprise and data center applications.

Adaptec has introduced a new enterprise RAID card that uses software-defined storage to support up to 32 PCIe 5.0 SSDs with speeds of up to 291 GB/s.