They do, it's called .32 NAA. North American Arms built their Guardian pistols to compete with Seecamp and after a few years wondered how they could improve upon the .380 and .32 ACP and they came back with bottlenecking the .380 down to .32. There's a lot of advantages to bottlenecking, improved feeding, higher velocity, heavier bullet for caliber vs a straight wall... it all made sense to do, but the issue was and always has been will the market take to a new handgun caliber?
New chamberings in rifles is always easily accepted because people generally aren't shooting thousands of rounds a year from them, so the ammo cost or availability isn't an issue that sways people away from something like .350 Legend, 6.5 Creedmore (talking the early days, it's caught on now), etc. Circle back to handguns and offer something that's not 9, .45, .38/.357, .44, or .22 and people act repulsed, they get physically ill at the thought of any handgun not in any of those caliber because "Good Lod, the ammo is so much and so hard to find!"
I mean, I can understand that with something like .357 Sig in a full size pistol where you can blow thru 200 rds in an hour at the range, but for a pocket pistol the size of the LCP, I don't even get thru a 50 rd box before I'm done shooting. So, whether it's in .380, .32 ACP, .32 NAA, it doesn't matter what the price of the ammo is, I shoot so little of it.
I suspect most people who own a pocket gun for conceal carry do not shoot them much.
So, why hasn't.32 NAA caught on even tho converting a .380 to .32 NAA requires a barrel change and a new recoil spring? I've explained it before, I'll explain it again in an abbreviated way:
1. No ammo companies make the ammo because they say there's not enough demand (due to lack of guns)
2. No gun companies make the guns because they say there's no demand (due to lack of ammo)
3. There's no big names in the media like Skeeter Skelton, Elmer Keith, Jeff Cooper, etc. writing articles or making youtube videos demonstrating the benefits of .32 calibers for self defense. The only one that really has is Chris Baker at LuckyGunner, but he didn't shoot .32 NAA because it's one gun and one factory load that's available.
It's really hard to get a caliber attention when nobody knows it exists and there's no interest because of bias in that .380 is more common, cheaper, and perceived as more powerful because it's bigger; these factors all contribute to .380 being "better."
"Hey, I can find .22 LR easier and cheaper than I can .32 ACP... that makes .22 better!"
I suspect that with the revival of interest in .32's that someone is going to offer something in the caliber that's more powerful than .32 ACP whilst being straight wall and rimless so as to increase capacity in stuff like the P365 or Ruger Maxx over 9mm/.380. I say the capacity is not important at all, after 10 rds if the threat isn't stopped you've got bigger problems than another 10 rds or more can handle. The .32 NAA is already the answer to a more effective pocket pistol caliber than .380, but nobody wants to make them for the reasons I just listed.