There's literally a seemingly endless amount of choices nowadays for pocket-carry CCW. I like a 9mm for my primary and just something I know is reliable as my bug (for me I really don't care about the BUG caliber as much as the reliability). I have been known to frequently
carry both my primary P11 and BUG Bobcat 21A in my pockets (even normal jeans) with a corresponding pocket holster. I think sometimes we tend to underestimate the pocket carry "potential or capability" if you will mistakenly thinking it has to be a mouse-gun of some sort. Honestly I would probably opt for a .380 but never have simply due to the fact that I have lots of 9mm, 45acp, 25acp, 22lr on hand and don't want to start allocating funds towards another caliber.
These two pictured below are easily concealable but, more importantly, easily accessible as well. However, I personally never pocket-carry my primary while driving my truck.