It's currently in testing, but there are issues with AMD GPUs (or at least the open source AMD drivers).
So if you head on over to Discord, there's a build posted in the Linux channel.
I've also been told by a number of people that DG works perfectly in Proton, although it seems there's a bug with Steam where you need to either reconfigure the target executable after adding a non-steam game, or remove all white space from the path.