Not sure what you mean exactly as this already exists and is written by the same guy @JakeBecker (who does amazing work) that Elixir LS is. However, I agree with your sentiment and I would say that editor/debugging support for the language would be my number one priority for improving ecosystem.
Elixir works great from the command line with basic text editor features and some better ones from the language server stuff. However, the language server and other editor support features could really use as much support as we can get. That’s going to drive adoption a lot and make development easier for more people. Editor integration is essential these days.