There have been fewer than 20 recorded cases of Group N. Whether a test would detect it or not is likely irrelevant as it is EXTREMELY rare. If you were in West Central Africa, Group O may be relevant, but otherwise, likely not.
I note from your previous posts that you have irrational concerns about HIV, and this fixation on very rare subtypes seems to be a part of that. If you need further information on testing or you have been at high risk for Group O, talk to an HIV specialist who can ensure you get proper testing.
If not, please consider therapy for your pervasive thoughts.
Any test will be conclusive at this point. 4th gen is the best test.