It takes a little skill and imagination and then NOTHING shows. First, tight pants might be an issue. Not necessarily but maybe. Think that through. Thin pants create more of an issue than thicker pants, like jeans. So that matters, too.
I pocket carried a Beretta 950BS 25 ACP pistol in my front pants pocket for years and years. I routinely placed a folded handkerchief in front of it to reduce the printing and then, one day on a whim, I picked up an old, thin leather card case and VOILA!!! It always looked square = wallet in front pocket = INVISIBLE. Worked like a charm and then one day I discovered pocket holsters - in a gun store in Tallahassee, FL in the early 1990s. Not sure how I missed them before, actually, but stuff happens. So, a little Kydex pocket holster worked perfectly but as I looked at my pocket I thought to myself, "Self, that would sure be less conspicuous with that leather piece in front of it". So I stopped the handkerchief trick but kept that leather piece and lo and behold, decades pass, and nobody has ever, not one time, pinned that gun.
Wait, I skipped a spot. I forgot to mention that I switched to a S&W M642 sometime after I left employment at a place where guns were forbidden but I was doing it anyway. I guess it was about 12 years ago I switched to the J frame, leather pocket holster, and same leather square in front of it to = wallet appearance. Yes, it is a little thicker than the little .25 auto but not to the extent that anyone could ever tell.
I happen to have developed a dislike of J frames for other reasons so I try to either carry a 2" K frame .38 or a 3rd Gen 9mm IWB or OWB but there are days when I still grab the J-frame and drop it in my pocket (it is easier to deal with, I admit that). Even sitting down it is invisible.
So, I will agree with the OP - it is very easy to pocket carry and conceal a J frame.