Are you sure they are fire extinguishers and not DS2 sprayers?
The decon spray bottle would contain DS2, which is caustic, I forgot if it’s closer to hypochloric acid or bleach.
(Neat fact that most people would never guess: instead of a pull pin to secure the handle against accidental discharge, the spray bottle has a lead plug that’s intended for the user to just squeeze the handle through in order to use it.)
A fire extinguisher contents may possibly be determined by its appearance. A label with the NFPA classification may or may not be present.
A red body with a hose or short barrel likely indicates water or dry chemical.
A rigid “horn” that swivels is for CO2.
A small silver body and metal hardware, with a short hose or barrel, is likely “purple K” for grease fires and combustible cooking by-products—found in kitchens but not CUCVs!
A larger silver body and hose is likely water, a neat can to have around as you can fill it with water and pressurize with a common air pump.
This has been your daily lesson in such things, brought to you by someone who’s been in both NBC and firefighter roles.