It's a client-side preprocessor essentially. The K8s cluster knows nothing about Helm as it just receives perfectly normal YAMLs generated by Helm on the client.
I really appreciate the k3s default with HelmChart type and operator installed. Makes working with charts simpler in my view
Yes, I use flux which has a similar HelmChart/HelmRelease resource. One of the things that took me a while to "get" with K8s is operators are just clients running on the cluster.