It seems many are focused on the time estimate. That was in creating the overall solution. About two months was to set up the infrastructure mentioned.

These often get developed side by side. GitLab, unit tests, api-server, nginx, cert-manager, deployments, integration tests, prometheus, metrics in services, grafana, alert-manager, log consolidation, work services and scaling, etc.

Just spinning up a cluster, nodepool, nginx, cert-manager w/let's encrypt cluster issuer, prometheus, grafana, can easily be done in a day. So, time estimates kinda depend entirely on what you mean by it.

Spinning up promerheus and grafana with automatic service discovery: one day. Making good metrics, visualizations, and alerts: everything from a week to a month or two. So, take the time estimates with a grain salt.