The 9x23 CP Elite was the forerunner of 9x23 Win. It was a semi-wildcat with brass but not ammo available from CP and no factory guns.
They offered two reamers, one was for chambering a new barrel, available from some places as a .355 short chamber that could be reamed to about anything of 9mm or .38 caliber. That was very close to what you would get now in a 9x23 Win barrel or chamber reamer.
The OTHER reamer was made to recut .38 Super chambers to handle the tapered case. This came out a bit oversize in some dimensions but seemed to work ok.
SOME .38 Super chambers on the large end of I.D. would handle 9x23 as is and were so used, with a lot of caveats about doing it only in a strongly constructed racegun that was probably already being shot with overloaded Supers.
Anecdote 1. I know one shooter who, when he did not want to be bothered loading .38 Super, shot 9x23 Largo aluminum Blazer, back when that was cheap. Tapered cartridge in a straight chamber, no problems.
Anecdote 2. I know another guy who started to reload 7.62x25 back when all that was available was corrosive Iron Curtain surplus and expensive WW .30 Mauser. He makes cases out of 5.56 or .223. This leaves him with a case head and rim diameter smaller than spec, but it does not affect his shooting.
Anecdote 3. There is interest in caliber convertible guns, things like .38 Super to 9mm P. They usually work pretty well, but the semi-rim to rimless change can affect extraction. I have had two, one required dedicated extractors, the other could be tweaked to handle both. You are going to a still smaller rim diameter, which might call for adjustment.
Conclusion: It seems to not make as much difference as you think. The various 23mm rounds and chambers have a lot of overlap at the tolerance limits. Since you can buy a .38 super barrel or gun off the shelf, that seems TO ME to be the way to get into it. I don't think searching out 9mm Steyr stuff to be worth the trouble and expense.
I repeat, the 9x25 Mauser will not fit a .38 Super magazine. Your 32.8mm = 1.29" and CotW says 1.39" = 35mm. That is a dead end.
Comment: Cartridge dimensions in the USA are commonly given in inches. It would be easier to kick this stuff around if I did not have to convert from millimeters. If you live in a metricated country, I will do it, but if you are in America, use of SI units just strikes me as pretentious.
What gun are you planning to use? There is a lot of industry support for the 1911 type, and not many other guns with long enough action for 23mm cases. I can think of the Witness/Tanfoglio large frame and the Sig Sauer P220.