Haven't used it myself, but every person I know that tried Pulumi ended up going back to Terraform. From what I'm given to understand it is fine for small projects, but runs into problems at scale.
Personally I don't like the default SaaS/account required model in Pulumi. I have lots of things to dislike about Terraform, but that isn't one.
Mind you too with either tool you (or your devs) will still deal with Dockerfiles and Kubernetes manifests, you just would use Pulumi or Terraform or whatever to manage them.
Lastly: I have done the jump from Ansible to Terraform myself. If you have a large amount of machines to manage and want to minimize transition pains then don't just use vanilla Terraform, but instead go for a platform like env0 or Spacelift, or at least use Terragrunt to manage your plans.