A couple modern pole barns have burned down in my area, as the OP said, they go real fast.
It would seem, that is largely because of all the exposed wood.
Steel siding, the other popular interior finishing material, seems like a good idea for fire prevention, but it actually has a zero fire rating.
I suggest the use 5/8" fireguard drywall, on as much of an interior as possible, at a minimum, on the ceilings of the shop areas, where a fire is more likely to occur. One layer of 5/8", gives you a 2 hour fire rating.
Finishing drywall ceilings on large pole barns requires special techniques, because these buildings move so much. You need to use some type of expansion joints, to allow for the truss up and down movements.
I like to use Trim Tex Majic Corner for this. It can give you a rubber joint over the top of the butted edges of the drywall, rather than in a space between them. And, it comes in 200' rolls, so it is always long enough. No cracking, or ridging, when I use this product.
The drywall may not prevent a fire from doing serious damage. But, it could slow the fire down enough to give the fire department a chance to save something.