I have been maintaining several self-hosted GitLab instances over the past 5 years, and it rarely takes me longer than 20minutes per update.
Their upgrade paths are clearly marked and well thought out. Their packaging methods are of great quality.
You will not regret going with GitLab.
I do straight VM installations unfortunately. I am too stupid for K8s. But seeing how the rest of their stuff is packaged, I suspect you will be fine!