It's kind of a pain, but you can use buildFHSUserEnv [0] to run a custom binary. If memory serves, this also works by writing the config for buildFHSUserEnv in a .nix file, running it with nix-shell, and then running the desired binary "the old-fashioned way."

[0]: https://nixos.org/nixpkgs/manual/#sec-fhs-environments