My LCP gets pocket carried in the summer heat in the side cargo pocket of my shorts using a Bearcreek holster with a leather panel attached to keep it upright.
It does flop/swing a little, but not too bad.
I've tried the same with my PM9, but it was too heavy and flopped a lot.
Its much better iwb at 3-4 oclock. Its a far faster and more secure draw from iwb and it actually feels lighter when carried there.
For me iwb is win-win for the little 9's.