GitOps (ArgoCD) with fly.io postgresql

Hello,
I wonder how to integrate this solution with GitOps ?
How would you easily provision a resource ? e.g. how to mixing configuration with GitOps ?

My first trial would be to create the initContainer / Job with a flyctl installed. And then run it.

I am not a user of Terraform or Crossplane and feel it is a bit overkill. What do you think ?