I think it is possible to environment.pathsToLink = ["/lib"]; and then
symlink /var/run/current-system/sw/lib into /lib. (That’s will
probably result in tons of merge warnings, but should work.)
Sounds like you are looking for buildFHSUserEnv.
Also, if you are just looking to run some random binary, you could give steam-run a try. It is basically buildFHSUserEnv wrapper with the
most commonly used libraries.
I should also note that the linking method is not very Nix-ish. It introduces impurity, and we prefer “file not found” error rather than a package working for some users and not others. (Due to wrong/absent patching and a combination of installed libraries.)