What functionality would you like to see?

"Firewall" is a source you can select in the Vercel UI, but it's missing in the Terraform provider.

Happy to provide a PR if you don't have time for this.

Example

resource "vercel_log_drain" "example" {
    delivery_format = "json"
    environments    = ["production"]
    sources         = ["firewall"]
    endpoint        = "https://url
}