Is your feature request related to a problem? Please describe.
It is possible that the existing Helm chart is not ready to be used directly, and the intent is for this to be copied. However, it would still be valuable to version this correctly and publish this to a registry. If it needs to be tweaked, consumers of this chart can use e.g. Kustomize to patch what is needed rather than having to sync and merge upstream changes to it.

Describe the solution you'd like
Suggestion is to:

Add a version to the chart that follows the tag
Publish the chart to e.g. ghcr.io so that it can be consumed as a Helm dependency

Describe alternatives you've considered
Git submodules could work, but is a clumsy and tedious method. Writing your own Helm chart from scratch, inspired by the existing one, which works but adds maintenance, also there may be subtle upstream changes requiring migrations which are not obvious.

Additional context