I got one of those icky grafted cactus, ripped the top off (tried to plant it, but it died) about 6 months ago. The base is a Hylocerus undatus - a dragon fruit.
So far it has grown two branches (is that the correct term?) that are ~ 15 inches each.
I have little hope that it will bloom or set fruit, due to my Zone. In either case, that would be cool.
I just like to try everything and when I found this is where dragon fruit comes from, I said .... neat. Go for it.