An easy way for me to grab packages is to go to the github “release” section and then right click on the one I want. Say for example I want to get a .tar file… I’d navigate to the release, right click, and copy the link to that file:
zig fetch --save git+https://github.com/Hejsil/zig-bench#bf749bad2ccaee2430e14c5fea7aba3197610723
error: unable to determine name; fetched package has no build.zig.zon file
Noticed the error mentions that it does not have a build.zig.zon file, so would probably need to add it manually somehow.