If it’s for a sunday afternoon hackathron then copy/paste will likely just work.
The unit of composition for dependencies is not modules, but it’s (otp) applications. Therefore the tools (like mix) for working with dependencies are built for that model. This is not done for lolz as well, given that has always been the unit of how dependencies are resolved within the beam VM and releases (see e.g. *.app files in _build or start scripts in releases). Each app declares it’s dependencies, so if ecto e.g. depends on decimal the vm makes sure to start decimal before ecto.
E.g. if your shared/file.ex depends on ecto, but your new app doesn’t have ecto (or decimal) around things will just blow up. These kinds of dependencies are not tracked on a per module level.
As you’ve figured out – or by using my suggestion of copy/paste – you can always forego proper dependency tracking if you want to. I however wouldn’t call that a good idea nor something that should be encouraged or be made simpler to do. All the primitives to do that exist and can be used, but you want to actively opt in to the fact that you’re sideloading modules and not depending on a third party (otp) application.
