An observation - -
An ankle holster for the 1903 / 1908 Colt Pocket Auto series would likely turn out to be less than satisfactory. Either one weighs 23 ounces empty. I carried a PPK in a custom made ankle rig for several years, and a pistol of that weight is a touch heavy for such wear. I dug out the old rig recently and wore it for most of one day, simply for nostalgia's sake. It seriously threw off my stride and reminded me why I broke down and purchased a brand new M37 Chiefs Special Airweight for the job some years back. Just about any handgun that weighs much over a pound, fully loaded, will have a similar problem.
Any ankle rig suitable for the Walther PP or SiG P230 or P232 should carry your .32 Colt well enough. Same with the IWB holsters - - An IWB holster is mainly useful to keep the pistol in place, and fit is truly not crtitical, so long as one may obtain a shooting hold before drawing. Any of the major holster makers can furnish a proper IWB holster for the job. I like the Milt Sparks Summer Special, but really, this is one application where I have no problem with using a fairly inexpensive nylon holster - - The belt and waistband provide the constriction necessary for concealment.
Back to ankle carry - - Please don't misunderstand - - I've always loved the Colt Pocket Autos - - In fact, there's a 1916-production .380 within reach as I type this.
These finely made pistols were state of the art at one time, but that time is long since passed - - kind of like the Walther PP/PPK series. There are several lighter and more powerful handguns, both auto and revolver, better suited for ankle carry. Every couple of months, though, I am seized with a retro mood and pack my old .380, either IWB or in an ancient brown belt holster. The tiny little sights are not very fast, but the accuracy of the elderly piece is fascinating.
Best regards,
Johnny