They're almost certainly putting a standard spec pi into a mil spec case. They might do some torture tests to weed out the bad ones / "uprate" the components.
The Broadcom BCM2711 is already rated -40 to +85C which is considered industrial or rugged. I have no idea what the rest of the components on the Pi board are rated for though.
Good point. Chip specs don't always represent hard operating limits, they are just the limits to what the manufacturer has tested to. Either the mfg has done some additional testing that the chip can work down to -40C or they've done something like else (like add a heater... not unusual for rugged machines).
