Juju doesn’t currently allow k8s Ingress Resources to be created directly by a charm. There’s a number of k8s resources that potentially fall into the same category.
To pick up another point, Juju doesn’t allow cluster wide resources to be created - Juju models correspond to a namespace and all artefacts from that model will go in the namespace. Allowing cluster scoped artefacts is not something we have modelled and it gets potentially messy very quickly.
So it is true that today Juju cannot do everything you can with say Helm. The trick is to carefully consider how to plugs the gaps - can we implement a holistic, model driven approach that scales well and is manageable; do we need a tasteful, pragmatic solution until we get more data to help drive a model driven approach; are there some things that will always be k8s specific that we need to just allow.
Maybe we can add a curated set of k8s resources (like Ingress) to the k8s specific yaml file the charm can produce. We already have Custom Resource Definitions and Secrets in there. The caveat would be that it would not be a free for all and at some stage we may deprecate some things in there (like secrets) when we do get to model such things.