Hi Mike, I think that yes, the gun you pictured has the ability to
spray Poly paints.

If my thinking is correct, Poly paints can be used to spray paint things
such as Guitars, etc.

As far as a small paint Sprayer for Home use goes, I myself never felt
the big need of having one, as I find them more a pain than a pleasure
to use many times.

I certainly wouldn't ever want to use one for indoor use, and I think
their biggest advantage would be when painting large areas quickly, with
a minimum use of paint (ie: Whole Houses, Barns, Utility Sheds, Garages,
etc)

In those cases, these sprayers are a huge help.
Mark