There's a lot of companies in that space, but yes, Gitlab is aiming to be the total package when it comes to development. "Idea, Issue, Plan, Code, Commit, Test, Review, Staging, Production, Feedback". Deployment is a part of that. I don't know much about Spinnaker, but it seems to have more features than Gitlab at the moment, although Gitlab adds features at a decent pace (release on the 22nd of every month).
Thanks for GitLab and the helpful link. It's also nice to see you're keeping https://about.gitlab.com/direction/ up to date. Lots of nice stuff in there, including ops features.