We use pistol calibers in pistols because rifle calibers don’t fit in pistols. If the platform works for rifle calibers, use a rifle caliber.
Well, 9mm carbines are definitely available, a few are not out of my budget, and ammo for target practice is easy to get and not too pricey... (Our Rural King stores were running a special on 9mm target ammo recently, which, plus links like the below, were some of the things that got me thinking 9mm.)
https://gundigest.com/rifles/affordable-9mm-carbine-options
Ummmm - I have a Rossi carbine that takes .38 Specials and .357 rounds...
The short barrel keeps it neat and is longer than a hand gun barrel which creates higher velocity and energy than when the same rounds are fired from a hand gun.
A friend has a rifle that uses 9mm rounds and loves it as an “in-between” weapon.
Says the person who never fired a 5.7x28mm.