I could proffer my own experience and the experiences of friends over the past 2+ decades. That would count as empirical evidence.
I could tell you about the first time I took Orgenon Sustanon and developed a large lump under my left nipple over night. That was under 24 hours. No pain, no itching, no swelling, no warning. Just gyno from thin air.
I could tell you about the first time I tried ugl testosterone in mct oil. Itchy, sweaty nipples within minutes. Again, gyno overnight.
I could show you pictures of the scars on my areolas from my gynecomastia surgery to prove that I have some experience in this area.
But you would have to believe me for any of it to matter. And to not believe me would mean you'd think I have some reason to make this up. This is a point of personal shame for me, not something to brag about. And what possible motive could I have to make this up anyway?
You presumably do believe that gynecomastia is a real thing and not a deep state conspiracy, no? I imagine you don't ask people who've developed gynecomastia over the course of, let's say, two weeks to two months to produce studies as evidence?
If this is truly a board that values harm reduction, then I've done my small part.