Infracost scans for Terraform code changes and checks over 3 million prices to create a simple, understandable cost estimate before any resources are launched.

Infracost Community

haven't looked into any details, but curious: what's the motivation/benefit of the migration?

The main reason is that it’s a precursor for adding support for other IaC (non-Terraform) tools. Other things it helps with are:
• building a multi-cloud cost calculator (<https://github.com/infracost/infracost/issues/840>)
• splitting our resources into a provider model, so they can be updated separately from the core CLI

Almost, one tricky resource is remaining. backup_vault