"Technically" dwarfism can occur in nearly any species.. but it's a genetic defect, so it wouldn't have to be a hybrid. It's just that, as far as I've been able to research, there are no dwarf ball pythons anywhere. No cases of dwarfism have been PROVEN yet. If that 800 gram female manages to breed successfully and throws dwarfed size snakes that otherwise seem healthy, then you MIGHT have dwarf ball pythons. It would be kind of a neat thing, as long as the snakes don't have underlying health issues along with the "dwarfing".
I have a small spider female, heavy spinner, who eats nicely, gets fat, but doesn't really GROW. I consider her stunted rather than dwarfed though, and since she's such a bad spinner, I doubt I'd ever breed her to anything to see about it.