Phoenix relies heavily on Elixir macros, so you'd first have to compile and then try to call the generated functions... But I'm not sure that makes a whole lot of sense as you'd be missing out of most of the benefits of Phoenix.

A more pragmatic approach is to use Elixir for the Phoenix specific parts, and from there call the other Erlang based languages for your business logic.

Yes, but it isn't exactly ergonomic. Elixir tries to namespace most of its stuff within an Elixir namespace, so you have to use that when calling functions out of it.

All the Elixir macro magic, however, will not carry forwards, so you'll have to be using the compiled Phoenix bytecode

Check https://github.com/josevalim/erl_phoenix

> Writing Phoenix controllers, templates, plugs, and live views from Erlang

These types are static and don’t end up in the runtime (which has no notion of types), so no. LFE will need its own solution, like Gleam.

A lot of what Phoenix has to offer comes from Elixir language features and the Mix build tool. To the extent it's possible I can't imagine it would be pleasant or useful.