Why does the package cache include both the nupkg and the extracted content?

[mus65]

I noticed that every package version in the NuGet cache contains both the nupkg file and its extracted content. It seems like building a project without a restore still works fine if I manually delete the nupkg file. So why is it there in the first place? And is it actually safe to delete the nupkg files?

I was looking into this because of Microsoft.Playwright which uses about 700MB in the cache, 200MB of which is the nupkg file. I wouldn't care about that locally, but in CI environments the cache has to be saved and restored between jobs, so the nupkg files can add up to a significant resource waste.