Nix does support symlinked store somewhat and there is a flag for that - NIX_IGNORE_SYMLINK_STORE. I had used symlinked /nix (with the flag) without any problems until I tried to install an R package which wanted to compile c++ code. At that point ld-wrapper.sh failed to recognize the path in the store after the symlink was replaced with actual ... More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.