GitLab's "Auto DevOps" with GCP Kubernetes Engine is pretty good at the 1 to 100 story. I clicked several buttons and got a google-managed k8s cluster that will pretend to be Heroku for me.

I've since outgrown the basic setup, but their docs showed me how to copy their "magic" configuration into my repo, and it was easy enough to edit to get what I wanted.

I kinda figured I'd be bypassing Kubernetes for this job, because I didn't want to spend a week setting it up, but they made it into an afternoon.