I’ve never used Helm charts. I learned K8S in a shop in which kustomize is the standard and helm is a permitted exception to the standard, but I just never felt any reason to learn helm. Am I missing out?

Sometimes the limitations of kustomize annoy me, but we find ways to live with them

Grafana's Tanka is a very underappreciated tool if you have to do something similar to Helm.

I suggest checking out Anemos (https://github.com/ohayocorp/anemos), the new boy in the town. It is an open source single-binary tool written in Go and allows you to use JavaScript/TypeScript to define your manifests using templates, object oriented approach, and YAML node manipulation.

You can read a comparison with Helm here: https://www.ohayocorp.com/anemos/docs/comparison/helm

P.S. I am the author of the tool.

Why do you want to stop using helm charts? Genuine question, as I'm new to Kubernetes and helm.