I have seen some of these vehicles suggested before but I thought I’d just put in my 2 cents.
-Bomb Squad Units  I saw that this was on the list for future updates.
-Medical Battalion  Basically a battalion chief unit but for medical calls instead of fire calls. Could be used for mass casualty calls.
-High Rise Units  Could be used in high rise fires and Other calls that spawn on the ”High Rise” POI.
-Collapse Rescue Units  Used when buildings collapses and partial building collapses.
-Brush Fire Units  Used for small wildfires. Could be used for large field fires, barn fires, etc.
-HazMat Ambulances  Used for Injures revolving around HazMat calls. Could be used to treat ”F” patients (HazMat related injuries).
-Corner’s Vehicle  Used to transport a corner to a death call.
Medical Examiner’s Office  Basically a morgue. Can hold corners and the Corner’s Vehicle.
So those are my suggestions for new vehicles and a new building. I can see how the High Rise units and the Collapse Rescue unit could be a waste of time since they are basically rescue and utility units. The high rise unit would only be able to respond to one or two calls.