This has been the case in the past but we are investing in our provider ecosystem. We built several first-party native providers that aren't based on TF: Kubernetes, Azure, Google. Now, we also encourage third-parties to build their integrations.
Here is a boilerplate repo of a resource-based provider: https://github.com/mikhailshilkov/pulumi-provider-boilerplat...
Here is a provider that is driven by an Open API spec: https://github.com/mikhailshilkov/pulumi-provider-boilerplat...
For simple use-cases, you've always been able to build Dynamic Providers in TypeScript or Python: https://www.pulumi.com/blog/dynamic-providers/
Please reach out if you want to build a provider and we'll definitely help you out.