This is a problem we, as a company, have thought about a lot, but we always concluded that Kubernetes is already the simplest abstraction of a distributed system that is feasible for the diverse needs that the biggest companies out there have.
We previously built a package manager for Kubernetes to abstract it in the simplest way possible `glasskube install app` but we failed because every abstraction needs to follow a "convention over configuration" pattern at some point. Also, we weren't able to monetize a package manager.
With Distr (https://github.com/distr-sh/distr), we have actually been able to help companies not only package but distribute and either manage or give their customers a way to self-manage applications. Our customers are able to land on-premises contracts at enterprises way faster than before, which is also a clear ROI for paying for Distr.
So, I don't think that you can get the flexibility of a distributed application orchestrator with a simple declarative YAML file if your target environments are diverse.