It normally doesn’t (unless you tell it to). It just deploys stuff at addDriverRunpath.driverLink and programs from nixpkgs already know to look up the missing drivers there
Unless I’m mistaken, in case of libGL specifically this isn’t only an NVidia limitation: libgbm should be impure · Issue #269419 · NixOS/nixpkgs · GitHub.
Note that use-cases like “using the host system’s (e.g. ubuntu’s) python with native extensions from nixpkgs” would remain broken because the host system’s python would load the old libc before it loads your wrapper.
Rearranging Nixpkgs so that we build against an older glibc but link a newer one for deployment like @vcunat suggests is more promising