Similar experience, we ended up building way more custom tooling and scripting than we wanted for our CI pipeline. We used Jenkins so speed was OK but I was really reminded that Kubernetes is not a PaaS it's Iaas. Basically we weren't really ready to go build a platform internally for our developers.

If you are curious I've been working on open sourcing some of the ideas we've built internally at my organization into some tooling built around deploying from GitHub: https://deliverybot.github.io/