I have seen it done, on a house a couple miles from me. The chimney goes up close to the wall, then is set out with a 30 degree fitting to clear the roof overhang, then straightened out to vertical again with a second fitting. I have never seen it close up, so I don't know what brackets are used. The bends are gentle enough that I'm sure they don't interfere with draft, and there are chimney cleaning rods that will easily flex enough to sweep it out.
I used to have an exterior Class A running up the wall, but my soffit extended only 6 inches, so I set the whole thing out far enough to clear the overhang with no bends. Chimney weight was borne entirely by the manufacturer's flat horizontal steel base bracket that the chimney sat on. There were two braces above the roof to keep it from blowing over.