I don’t see how they’re orthogonal. They both have the same goal of removing the link between a transaction and the originator’s IP (or persistent Tor/I2P address). Is there another goal that we wish to achieve that I am missing?
If the first hop is done through a private broadcast, then it achieves the above goal. I’m not sure how you mean “in general across the network” to be an improvement. Dandelion requires multiple hops and other nodes to be honest throughout the hops to achieve the same goal.