When Eelco Dolstra, father of Nix, descended from the mountain tops and enlightened us all, one of the main commandments for Nix was to eschew all uses of the Filesystem Hierarchy Standard (FHS).

Farid Zakaria’s Blog

Nix was designed to abandon the Filesystem Hierarchy Standard (FHS) for reproducibility, but graphics drivers expose a fundamental exception. Because user-space libraries like libGL.so must match the host kernel and GPU, NixOS and Home Manager introduce an intentional impurity: a global convention path at /run/opengl-driver/lib. This effectively re-introduces an FHS-style convention. Users running Nix on non-NixOS Linux distributions are left without this workaround, hitting the classic 'cannot open shared object file' error. Available workarounds include nixGL, manually setting $LD_LIBRARY_PATH, or symlinking host drivers to the expected path.

Nix is a lie, and that's ok

Nix is so great I forgive this exception :)

Theory versus Reality
It’s more important to have a working graphics setup, than to adhere to the best practie concept, unfortunately.