Does helm.v3.Release not support transformations like charts do?

No, you could try to use post rendering but I hit an issue with passing args to it.

https://www.pulumi.com/registry/packages/kubernetes/how-to-guides/choosing-the-right-helm-resource-for-your-use-case/ has more information about the options here

@gorgeous-egg-16927 despite the options above, please still fix the helm release post rendering issue so that at least provides another escape hatch for transformations, albeit a less rich option compared to helm chart transformations. 🙏