Allow devenv project (outputs) to be (remotely) importable in another devenv or flake

[clotodex]

Concrete usecase: I would like to use an output of a devenv project in my nixos config.
General usecase: Extending projects with builds from other repositories

Right now all importable projects need to be a flake afaik. So the only way to make this work is to wrap the devenv into a flake, correct?

Are there any other ways to do this or ideas on how devenv could become compatible here?