I think I kind of qualify for this question. My first carry gun was my Glock 29 back in 2008 and I used a kydex shell IWB with leather inside, was from a small holster maker that is no longer in business. It worked pretty well but eventually the Kydex cracked from years of use. I got an Alien Gear holster that was similar but in my opinion, it was never quite as comfortable. It worked.
Eventually I moved to a full leather IWB, this one made by Frontline. Grabbed this because it was being offered on a big time sale, around $30 I think. It was the most comfortable yet.
Here's where it gets relevant... eventually I moved to a different carry gun, a Walther PPQm2. And right in to the leather Frontline G29/30 holster it goes. Fit GREAT. It's IWB and retention is terrific, comfort is high.
So I'm still using a holster made for a Glock 29/30 for carrying a PPQ. And bonus! When I elect to carry my S&W 469... it fits also. Retention not quite as secure, but it works.