Ian Fleming had James Bond carrying a .25 caliber Beretta early on. The British gun expert Geoffrey Boothroyd wrote Fleming and said the .25 caliber gun was only suited for a lady’s handbag and suggested the Walther PPK. Of course the .380 PPK isn’t that powerful, but it’s a big step up from a .25 caliber.
Bond used a .32 caliber PPK. They were all .32 caliber for a very long time.
Not sure I see much value in a gun smaller than an LCP. It reaches a point where it is darn hard to get hold of and use.