> looking for a small metal garden sprayer (that can be directly heated) rather
> than my solar heated sprayer I use for shower
Is this what you're looking for?
http://www.hotcampshowers.com/campfire___stovetopOf course, Coleman has made propane showers for years; a battery-powered submersible pump in a pot of hot water would do the trick, too. Not hand-powered, of course, so you have to have batteries.