Although that may be true, the quota at least on GitHub depends on what you're quering. We worked directly with GitHub and a complex enough organisation hit with a GraphQL query can actually hit your hourly app limit before you even get a response.

As for GitLab, having hosted it for medium size organisations (~200 devs) and seeing how monorepo's work (they don't, we had GitLab's team show us that one page view made 50K db queries on our setup), please consult with your local admin team before firing GraphQL at it.