I hate to break the news to you, but even after you looked it up, you still misspelled Vihtavuori.
I don't see 3N37 used in Nosler's 9mm data where it shows it being the most accurate. Please point to examples where 3N37 is the most accurate powder in Nosler's data. Surely you didn't just make this up, did you? (When Nosler does indicate which load or powder is the most accurate, we have no way to know HOW MUCH more accurate. Technically 0.01" difference would be more accurate, but is meaningless in the real world.)
Which Hornady data shows 3N37 as most accurate? Where is this appendix in the Hornady manual that shows 3N37 being the most accurate? I don't see it in my 10th edition. Please show me where to find it. Thanks.
The article you posted shows 3N37 producing very small groups in a Glock. But that's one Glock. And it's not even a Glock barrel.
You'll be proud of me. I did some legwork on my own. If you followup and look at that author's second article on 9 Major accuracy, you'll see 3N37 produced some of the largest groups in a different gun. So your claim of it being the best in most handguns is not supported.
https://www.ssusa.org/articles/2020/4/28/accuracy-of-9-major-handloads/
Is there other data you can direct us to that shows 3N37 producing the best accuracy?
I get the feeling you made up that part about 3N37 being the most accurate in . . . "almost any carry size pistol that uses a locking action." You only provided one example and your other 'examples' (Nosler, and still waiting for your Hornady information) don't support you.