You might be able find an exception -- there is no approval process for HIG in Mac apps. But you will not find an exception (v1.0.1 or later) in an app that has any meaningful user population, or is of any meaningful quality.
Ignoring HIG without good justification is a strong garbage signal. It was a surefire indicator of a crap Windows port back in the 1990s, but I don't think that's even a thing any more.