M.2 boot drives for servers have been popular for years. There's a whole product segment of server boot drives that are relatively low capacity, sometimes even using the consumer form factor (80mm long instead of 110mm) but still including power loss protection. Marvell even made a hardware RAID0/1 controller for NVMe specifically to handle this use case. Nobody's adding a SAS HBA to a server that didn't already need one, and nobody's making any cheap low-port-count SAS HBAs.