I believe it could be done via classes or packages, but only if the providers have the discipline to design it like a rest service, and the users then have the

I believe it could be done via classes or packages, but only if the providers have the discipline to design it like a rest service, and the users then have the discipline to only use it like a rest service. Each package needs a small, consistent interface, with no way to interact except through that interface, with that same style of consistency across all libraries in the same way. The code must be isolated at runtime, so it can't steal resources from other pieces of code in the monolith or cause anything to crash. It can only respond to requests along the interface, either successfully or unsucessfully. So, theoretically possible, but in practice difficult once you add humans to the mix.