There is currently no really nice way to mix Helm and Kustomize for consuming charts you do not fully control the contents of..
Anything is possible with a plugin, but one looses the flexibility of being able to pass in parameters.
Embedding the Helm chart into the kustomize also had drawbacks (like being about to access the Argo Build Env or pass along input variables)

Maybe a first class way to define and use a post-renderer?

Upstream issue: https://github.com/argoproj/argo-cd/issues/7623