Do they make a high temperature paint with sparkles or glitter to paint the inside of a firebox?

no.

in fact, all paint vehicles are flammable, and you are buying trouble if you paint a firebox.

not to mention glitter is plastic flakes.

there should be nothing in a firebox except firebrick and refractory compound.

I'm looking for a glimmer paint that is a 1 step process. I've heard about it but can't seem to find it at any of the paint stores. Not the old fashioned metallic faux finish, but something thicker with a little shimmer & texture.