Thanks for the kind words, and it's fun to hear that you're local! I think I should have clarified more about my view of an assembly compiler:
A "bespoke backend, going to assembly directly" does not preclude the option of integrating with an Erlang/Elixir project. In fact, I think that you could do so via ports or NIFs in such a way that the caller wouldn't know the difference. I think of the Erlang JSON libarary, jiffy. It's largely implemented in C for performance, but the language it's written in doesn't seem to matter in practice. As long as there is an easy way to integrate it into your Erlang/Elixir project.
I think an "Elm on the server" solution would work much the same way. Focused on making a clean integration point—then choose whatever implementation leads to the most performant and reliable artifact.
A "bespoke backend, going to assembly directly" does not preclude the option of integrating with an Erlang/Elixir project. In fact, I think that you could do so via ports or NIFs in such a way that the caller wouldn't know the difference. I think of the Erlang JSON libarary, jiffy. It's largely implemented in C for performance, but the language it's written in doesn't seem to matter in practice. As long as there is an easy way to integrate it into your Erlang/Elixir project.
I think an "Elm on the server" solution would work much the same way. Focused on making a clean integration point—then choose whatever implementation leads to the most performant and reliable artifact.