The second requirement is actually probably the most important - if someone that just set up ArgoCD, Flux, or has their own GitOps pipeline, how much of a headache does using a new compile step present?

Lots of things are simple in isolation: want to use Cue? Just get your definitions and install the compiler and call it and boom, there are your k8s defs! Ok, but how do I integrate all of that into my existing toolchain? How do I pass config? Etc, etc.

The best, fastest tool won't win. The tool that has the most frictionless user story will.