I guess it depends on how fast you want to be able to draw from a pair of jeans pocket. My PM45 with a 5rd mag has a height of 4.49". I can draw it from my front pocket though I would not pocket carry it wearing jeans by choice. It's not a lightning fast draw but not cumbersome either. The P9 has a height of 4.5" so I think it would be doable also.
I typically only pocket carry 9mm or larger in the Summer and I have about 8 pairs of cargo-like shorts that I wear because there's plenty of room in them.
Now my P380 is almost small enough to fit in my jean's watch pocket