This kinda exists now with the newer partial clone options: https://github.blog/2020-12-21-get-up-to-speed-with-partial-...
(Edited because submitted too early :D)
(Edited because submitted too early :D)
For example, in all of my repos, I have massive test code. It usually far surpasses the implementation code.
It would be nice to be able to clone just the one 300-line implementation file, as opposed to the several thousand lines of test code.
Also, the “aggregate” workspace thing that SourceSafe used, would be a great help, for a lot of dependency hell issues.