+1. This would be an incredibly useful tool when I have to search private company repos I'm unfamiliar with. Currently I use GitHub's 'search current repo' functionality but it's not great.
I often browse private code in github when I intend to store or share links to certain lines in our codebase. e.g. to use in tickets or PRs, or during Slack discussions.
This tool is to quickly investigate a codebase you've never seen through the façade of a familiar tool.
A "personal private repository" isn't code that you've never seen or are unfamiliar with.