Kim has a piece on pocket pistols,

'Handy, but don't depend on them', but I think he missed one of their prime reasons for being: winter.  A heavy coat can make it difficult to access your belt-carried sidearm, so something that'll fit in a pocket  and is easy to reach and draw can be very handy.  No, it won't be as powerful as, say, a M&P or a Sig P320, but it'll be enough to, at the least, buy you time.