Sandboxing is merely a stop-gap to reproducible builds (I hope). Nix style multiple instances of the same version of an installed package will lead to better reuse, thus faster builds.
If the fingerprints can be made precise enough, binary caches can be distributed from trusted parties, similar to what other package managers do.
If the fingerprints can be made precise enough, binary caches can be distributed from trusted parties, similar to what other package managers do.