The current email templates are very simple and offer only the built-in Go template functions. I'm used to Helm, where sprig is available, with many useful functions. Currently, even a simple use case as converting a string to uppercase is quite hard to implement without e.g. creating multiple versions programmatically and putting them in the user metadata.
Paweł Cembaluk suggests enhancing email templates by integrating more functions, similar to those available in Helm's sprig library. He finds it difficult to perform simple tasks like converting strings to uppercase without additional programming.