I just start integrate erlfmt from What’s App into mix formatter plugin here GitHub - wingyplus/erlfmt_formatter_plugin: Erlang erlfmt formatter plugin for Elixir. Use case is for Elixir project that has Erlang code mixed in project. The library doesn’t publishing on hex.pm yet since it’s in testing & adjusting an error state. So you can temporary installing via github at the moment.
Hopefully this could be useful. 
