A lazy-clone virtual filesystem? That is way out of scope for this project. FUSE needs a userspace daemon and Elisp is not a practical choice for implementing it - you're gonna need to build a CLI companion. Ripgrep and LSP both need access to most or all files. You'd have to fetch every blob, at which point you're fighting the GitHub API's rate limits - not worth it, easier just to clone. CoW would add a local mutation layer, which means state management, conflict detection, and by the time you get there, you're reimagining git itself.

The point about ripgrep worth considering though - maybe search command that hits the search API would be nice. There are some constraints though - 30 requests/minute (I think); it would only work with indexed branches (non main branches may not be); it only indexes files under certain size (something like less than 400Kb); there's no regex; All that makes me think maybe it's better to make it easy to clone/jump to cloned repo instead.