[theamk]

"git worktree" shares a .git folder between multiple checkouts. You'll still have multiple files in working copy, but at least the .pack files would be shared. It is great feature, very robust, I use it all the time.

There is also ".git/objects/info/alternates", accessed via "--shared"/"--reference" option of "git clone", that allows only sharing of object storage and not branches etc... but it is has caveats, and I've only used it in some special circumstances.