With latest Raspberry Pi Compute Module 4, the Raspberry Foundation added NVMe SSD RAID support via M.2 (PCIe 2.0) interface.
GeeekPi M.2 NVME SSD Storage Expansion Board for Raspberry Pi 4, Only Support M.2 NVME SSD (Pi Board or M.2 NVME SSD NOT Included) : Electronics
DS-1302, High Performance & Expandable (DS Series), Rugged Embedded Fanless Computer, Products
QDA-UMP4, Install an M.2 PCIe 4.0 NVMe SSD in a U.2 PCIe NVMe SSD slot for PC and NAS
Geekworm NASPi V2.0 2.5 inch SATA HDD/SSD NAS Storage Kit with Safe Shutdown & Auto Power On Function for Raspberry Pi 4 Model B(Not Include Raspberry Pi 4) : Electronics
FINALLY! NVMe SSDs on the Raspberry Pi
Radxa Taco Developed Baseboard Support for The Raspberry PI CM4 to Provide a NAS/Router Solution : Electronics
X876 NVMe M.2 SATA SSD NAS Expansion Board for Raspberry Pi 4
DS-1301, High Performance & Expandable (DS Series), Rugged Embedded Fanless Computer, Products
NVMe SSD boot with the Raspberry Pi 5
JBOD vs. RAID: What Are the Differences?
Geekworm NASPi Gemini 3.5 Dual 3.5'' SATA HDD NAS Storage Kit with DC
Cablecc USB4 USB4.0 to Dual NVME AHCI NGFF M-Key SSD Raid Docking & Displayport Cartridge Adapter : Electronics