Yay for GitLab and Forgejo/Gitea.

My previous two startups used GitLab successfully. The smaller startup used paid-tier hosted by gitlab.com. The bigger startup (with strategic cutting-edge IP, and multinational security sensitivity) used the expensive on-prem enterprise GitLab.

(The latter startup, I spent some principal engineer political capital to move us to GitLab, after our software team was crippled by the Microsoft Azure-branded thing that non-software people had purchased by default. It helped that GitLab had a testimonial from Nvidia, since we were also in the AI hardware space.)

If you prefer to use fully open source, or have $0 budget, there's also Forgejo (forked from Gitea). I'm using it for my current one-person side-startup, and it's mostly as good as GitLab for Git, issues, boards, and wiki. The "scoped" issue labels, which I use heavily, are standard in Foregejo, but paid-tier in GitLab. I haven't yet exercised the CI features.