As of August 28th, 2025, Expert LSP has been released: https://github.com/elixir-lang/expert
Although still a work in progress, the plan is for the other three LS implementations to be archived. I may try to come up with a new way to track Expert's featureset, but I would probably contribute that back to Expert as documentation.
As of August 15, 2024, it's been announced that the three projects bein compared here will soon merge! See the official Elixir blog post for more details: https://elixir-lang.org/blog/2024/08/15/welcome-elixir-language-server-team/