Git makes it impossible to automatically share artifacts between independently acquired repositories, because there is no hint as to them having a common base or not.
Attempts to merge the artifacts that do not have a large part of their commit graph in common leads to extremely long search times to identify a shared root.
The ability to share the artifacts between repositories would be very useful especially for very large repositories like the Linux kernel, the Chromium project or nixpkgs.
For that purpose, repositories could come with an identifier that persists throughout renames (and can be optionally set by the user) which can be shared between repositories with a large common base, indicating to Pijul whose repositories attempting to share the artifacts of could be advisable.
For more info on a usecase and the problems with git, see https://github.com/NixOS/nix/issues/1836.
Of course the same performance issue may not exist with Pijul in the first place, but I don’t understand enough about Pijul’s storage architecture to determine that and thought it important to bring up before 1.0.