This sounds like Cross-Repo Code Navigation [1], which we do support, though only for Python at the moment. And you're right that it does not use the same search index under the covers — OP is specifically describing the index for "search box"-style code search across a large set of repositories (org-scoped, global-scoped, me-scoped, etc). For Code Navigation, we have a _different_ set of interesting and bespoke indexers and storage formats. I've posted some links here if you want to learn more: [2]

[1] https://docs.github.com/en/repositories/working-with-files/u...

[2] https://news.ycombinator.com/item?id=34693181