Timoni seems to be focused on managing applications by evaluating CUE modules stored in OCI containers, and produces OCI containers as artifacts. It looks like Holos is more of a configuration management solution that also uses CUE, but produces rendered Kubernetes manifests instead of OCI containers. Holos narrowly focuses on integrating different types of components and producing "hydrated" manifests while relying on other solutions (Argo/Flux) to apply/enforce the manifests.