It's hard to make anything small fire-rated, due to thermal inertia (or rather, the lack thereof).

I'm surprised I haven't seen a NAS with the hard drive enclosure fire-rated.

How about a fire-safe with a female USB port on the outside, and a male USB port on the inside - both connected? That would be cool.

Some companies sell fire-safe & waterproof HD enclosures which you can use without moving the disks.

You would need one with the mass of a fire safe which somewhat nullifies the point.