I have not used quadlets in a "real" production environment but deploying systemd services is very easy to automate with something like Ansible.
But I don't see this as a replacement for k8s as a platform for generic applications, more for deploying a specific set of containers to a fleet of servers with less overhead and complexity.
But I don't see this as a replacement for k8s as a platform for generic applications, more for deploying a specific set of containers to a fleet of servers with less overhead and complexity.