I believe this Elixir based project is influenced somewhat by Rails:

https://hexdocs.pm/phoenix/overview.html

Not tried it, but I came across it whilst updating my knowledge on what was out there that was similar/influenced and/or opinionated like Rails.

Also, off topic re: Elixir, found this for Rust:

https://loco.rs/

I guess it's difficult to justify moving away from tried and tested Rails for a new startup if you know how to spin things up with it already.