I'm pretty sure Elixir is looking to make some pretty significant changes to add some kind of static typing in the near future, so I definitely wouldn't put it in the "done" category.
Older Elixir would 100% backwards compatible and any type system (if there is one,) would be gradual.
https://elixir-lang.org/blog/2022/10/05/my-future-with-elixi...
It's an optional feature.