https://github.com/purerl/purerl & https://purerl-cookbook.readthedocs.io/ for more information. Join the PureScript discord and the #purerl channel if you want help.
In terms of the typing itself, it's exactly what you get in all of PureScript, strict static typing with no `any` or the like. Using `Pinto`, the de facto OTP layer in PureScript your processes are typed, i.e. their `info` messages & state are typed, which means that they are all much more like strongly typed state machines than anything else.
You can see an example of a basic `gen_server` here:
The differences aren't very big in terms of what you'd expect to be doing. One small thing to note is that the `GenServer.call` expects a closure to be passed instead of having the split between `gen_server:call` & `handle_call`, removing the need for synchronizing two places for your messages being sent and handled.
0 - https://github.com/purerl/purerl
Edit:
As an upside you also have PureScript for your frontend, so you can just write everything in the same language regardless of how much frontend work you expect to be doing. PureScript has great bindings and a great story around React (it actually fits better since it's a purely functional language, so things like "You can only do effects in `useEffect`" actually are enforced and make sense) and also has its own frontend framework in Halogen which is very nice.
There was actually a developer working on a subset of Elixir that compiles to JS called Elixirscript[1], but development seems to have stalled. Another functional statically typed compile-to-js language which targets the BEAM vm is Purescript through the Purerl project [2].
If you're going to compile to JS though, there's an argument to be made that you might not want to target the BEAM at all. You could potentially run your entire backend on something like Cloudflare Workers, which has over 200 points of presence around the world, so latency is about as low as possible. The other CDNs have their own competing worker runtimes as well (e.g. Cloudfront functions, Netlify functions, etc.). These edge worker runtimes also have the benefit of not charging for each individual region in which you operate. You can also run any language which compiles to WASM like Rust, Assemblyscript, or Grain [3] on these edge runtimes. The only missing piece for me is a distributed database, but it looks like Cloudflare at least is working on that [4].
[1] https://github.com/elixirscript/elixirscript
[2] https://github.com/purerl/purerl