I honestly don’t know. I have mainly so far done it for personal interest.
From what I can see and through some simple tests Nx seems to work well with Erlang. I have at least testade the simple examples given in the “Nx for absolute beginners” and “Up and running Nx”. I made a very simple Erlang module called nx which just passes all the calls through to Nx. As there a re no macros in Nx there are no problems calling it from Erlang.
The thing to remember is that Elixir runs on top of Erlang/BEAM so everything it does goes through them so it can all be done directly from Erlang. The question is more what the interface looks like. As soon as it includes Elixir macros then it becomes more complex to handle. And the module names don’t help. 
I must also admit I have another interest. I have been testing from LFE 
This is about the same as for Erlang but if I ever get to the stage of needing macros then LFE is much easier than Erlang. And I like the parentheses.
We shall see how it goes with the book.
