How do you manage 100s of microservices, multiple branches and environments in your project? Atlassian Bitbucket? Gitlab? Github actions? In-house pipelines? Please add any other variants in comments as well.

PS we (by the way) built the internal server-less ci/cd system on top of AWS CodePipeline and AWS CodeBuild and described our experience here - Story of CI/CD in our startup: from a few micro-services to full-blown multi-tenant, multi-account, multi-region systems.
We are really interesting to know you experience.