For whatever it's worth, I tried one of those "ecological" fire extinguishers in lieu of a real dry chem because I've used a dry chem before and the mess is horrible.
One day we had a small galley
file. Quite contained, just on the stove top, so I had a spare second to grab the eco-extinguisher. The trigger broke off in my hand and nothing happened. So those are a great idea but at least for me I'm glad I didn't actually need it.
You can also buy Halon extinguishers from aviation shops. They're legal
in military and aircraft cockpit
applications. We probably have six dry chems in the cabin
all over the place in our 36' boat, and there's a Halon closest to the galley and engine