Yes, Kata started as clear containers. And yes, the main purpose is compatibility with containers -- though generally speaking, adding layers to the cloud stack

Yes, Kata started as clear containers. And yes, the main purpose is compatibility with containers -- though generally speaking, adding layers to the cloud stack never helps to make a deployment more efficient. On kraft.cloud we use Dockerfiles to specify app/filesystem, but then at deploy time automatically and transparently convert that to a specialized VM/unikernel for best performance.