I think this is considerably more difficult than they think, genomes are more than just throwing genes together. It’s a finely tuned symphony made by evolution, epigenetic silencing and signaling, gene position. I suspect it doesn’t work at all but if they got something it would be more like the centaurs in Fallout. I also think there are ethical questions whether that baby “mammoth” being born would ask to be create…
We breed zillions of animals without ever asking them for consent. In part because it's impossible. Those are some brand new goalposts.