Hi :) This should be possible, but I have not done it yet myself. For the time being, you would have to create a barebones NixOS project and build on that based on own research.

I have plans for making a dedicated starter to provision Elixir/Phoenix projects as a "1-click" starter

I know a feature is 'no funny abstractions', but would something like devenv.sh help achieve more or less easy support to multiple languages quickly?

Yes! I look very much forward to experimenting with implementing Devenv on some upcoming starters :)

BTW, I just published the "Migration" starter a couple of seconds ago.

It's meant to help you with loading your current project that will be compliant with Shipnix.

The documentation is slightly outdated, but it's mainly a guided flow.

https://docs.shipnix.io/starters/migration/

You could run the generated "shipnixifier" script in a temporary folder and manually merge it to your project, and then provision it.

Feel free to reach out through the support if there is something I could help you with.

Will you be adding other possible cloud providers (some people already have a relationship with google cloud/amazon, for example)

Yes, I have plans on adding more providers in the future. I am especially interested in priotitizing a provider with GPU instances like Vultr. AWS/Google are also on the agenda.