It seems like your primary concern with Nix is that there can technically be collisions in the hash identifiers in the Nix store (?). The probability of finding

It seems like your primary concern with Nix is that there can technically be collisions in the hash identifiers in the Nix store (?). The probability of finding a collision in sha256 (what Nix uses) is negligible. We use this assumption all the time in modern cryptography. Nix has plenty of flaws, but the probability of hash collisions isn't one of them.