I don't think you can provide all the features of Kubernetes while reducing the complexity. What is possible is to support a subset of the features of Kubernetes while making it easy to use.

https://github.com/openrundev/openrun is a project I am building. It supports declarative deployments, on a single-node with Docker or onto Kubernetes. The target use cases is limited to standalone web app, like internal tools. No support for stateful services, you manage stateful services yourself. With that simplification, OpenRun provides a much easier developer experience.

I look forward to the evolution of your project into a less standardized Kubernetes as end users request more and more features of your project.