You mean just as easy to write/test/deploy a custom resource as it is to use a ready one? I disagree. I think there's a few days of work of difference in that case.
Just add a few lines of code for create, update and delete for your resource.
For Node and Python, you can write them in the web console, test them, copy the code to your git repo and export the SAM CF template for your CI/CD process.