I made a thing, https://gist.github.com/maxnordlund/18a289c1dbcc6639e40af4819d39beda
It's a script to adjust/fix Elixir beam files from asdf so that LSP go to definition works.
Download it and run it like so `elixir adjust_beams.exs`, just make sure you use the elixir binary you want to fix.

An Elixir script to fix/adjust source location in all Elixir beam files so that elixir_ls got to definition works. The sources must be present, e.g. asdf installtions works but brew does not. - adj...
It’s using the pre-compiled Static PHP artifacts, but if this works well, and there’s interest, I’ll set up my own build system and hosting, so I’m not taxing their resources and can offer different combinations of extensions.
So, I decided to re-work it to use Static PHP, and after struggling with differences between versions of bash, I've finally got it working and ready for others to try out.
Be warned, it’s experimental!
"If there is one thing that confuses newcomers to Common Lisp, it is the interplay of built-in CL functionality, add-ons like Quicklisp and ASDF, and what all the words mean." by Cees de Groot
https://cdegroot.com/programming/commonlisp/2025/11/26/cl-ql-asdf.html