If it's any help: I use docker multistage to build a barebones alpine docker image. It uses distillery.
I based my dockerfile on https://gist.github.com/bsedat/16cb74ebc8ab0ed61ac598a129b0a...
Blogpost: https://zorbash.com/post/docker-multi-stage-elixir-distiller... (I'm not the author)
I just got the same setup this week. Docker multistage builds are amazing and make builds super small and awesome. You can ship releases without having to install Erlang or elixir on the imag, and just use what distillery has. Distillery really is amazing.
Releases and deployments with Elixir are still the area that needs most work, but it's nothing that would ever prevent me from using it. I have several in production and once we figured it out, it was easy peasy from there on.
We have some on DO and some on Heroku for clients. Both work well enough.
I will read more libraries; hopefully I can find some which use flow.
I have used distillery but I find myself going down a pretty big rabbit hole just to release something which in most languages is pretty simple. I will look at it again.