GitLab team member here.

> How many distros now have their own GitLab instance?

Open Source project partners are listed in https://about.gitlab.com/solutions/open-source/partners/

More insights into GitLab for Open Source in https://about.gitlab.com/solutions/open-source/ and the Open Source program handbook page in https://handbook.gitlab.com/handbook/marketing/developer-rel... -- created an MR to update the section at the bottom with Hacker News examples. https://gitlab.com/gitlab-com/content-sites/handbook/-/merge...