Disaster brigade additions, such as a chainsaws with their own minigame(?) shovels to establish firelines, or possibly some sort of excavator vehicle to then establish one.
An idea as well I had for firetrucks is levels of water pressure, the higher the pressure the easier the fire is to put out, however it makes you run out of water quicker therefore having to refill at a hydrant/body of water. I have lots of ideas for this certification that I can't just expand all in one suggestion so.