> Suppose you control the entire stack though, from the bare metal up. (Correct me if I'm wrong, but) Toro doesn't seem to run on real hardware, you have to run it atop QEMU or Firecracker.

Some unikernels are intended to run under a hypervisor or on bare metal. Bare metal means you need some drivers, but if you have a use case for a unikernel on bare metal, you probably don't need to support the vast universe of devices, maybe only a few instances of a couple types of things.

I've got a not production ready at all hobby OS that's adjacent to a unikernel; runs in virtio hypervisors and on bare metal, with support for one NIC. In it's intended hypothetical use, it would boot from PXE, with storage on nodes running a traditional OS, so supporting a handful of NICs would probably be sufficient. Modern NICs tend to be fairly similar in interface, so if the manufacturer provides documentation, it shouldn't take too long to add support at least once you've got one driver doing multiple tx/rx queues and all that jazz... plus or minus optimization.

For storage, you can probably get by with two drivers, one for sata/ahci and one for nvme. And likely reuse an existing filesystem.