I think the difference is that CDK “compiles” down to CloudFormation. Whatever you do it still has to be valid compared to a random application that can do whatever whenever. OFC I’m ignoring the way CDK makes it easier to use (and sometimes encourages) custom providers backed by Lambdas.

Agree and also have to consider that there is a need for solutions for cloud providers other than amazon.

Have a look at CDKTF [1]. It’s a wrapper around Terraform that lets you use CDK-style semantics that compiles down to a Terraform plan. Every Terraform provider can generated into a CDKTF library.

[1] https://learn.hashicorp.com/tutorials/terraform/cdktf