My highdea is a firetruck that has cans of compressed nitrogen, and a firehose of sorts that’s got some resistive heating elements lining all the inside of it (that can be turned on or off). Then it just dumps out nitrogen at a huge CFM/PSI/whatever, displacing the oxygen quickly enough to blow out the fire, but not long enough to suffocate the immolator.
Basically a huge, super powered hand dryer. That chokes the fire. And a 50/50 shot as to whether it’s nice and warm or freezing fucking cold.