I don't and never have worked at Pulumi, but I've read the open source code and can see that the Pulumi engine is distinct from what HashiCorp seems to call "Te

I don't and never have worked at Pulumi, but I've read the open source code and can see that the Pulumi engine is distinct from what HashiCorp seems to call "Terraform CLI" or "Terraform Core". But there are indeed repositories in their GitHub org which started as forks of Terraform providers, as I said. Pretty good strategy to start from all of the generic glue code somebody else already wrote and then adapt it to a new engine, because that's the undifferentiated heavy lifting that needs to be done regardless of the engine design.