Boot to internal drives on TS-453D

[mconstable]

Has anyone ever figured out a way to boot DIRECTLY onto the internal drives of a TS-453D (or similar spec) machine?

I have used an external SSD with success via ZFS Raidz-1 with two internal SSDs of the same size, but I'd really REALLY like to eliminate the need for an external USB device. My TS-453D is up for sale, but I like the form factor and would buy more of them for a matching cluster if, and only if, I could boot directly off the internal drives.