5.7x28mm is what the FN Five-Seven pistol is chambered in, and if I'm not mistaken, the 4.8x30mm round made for the MP-7 was also planned to be put into a pistol, although that project was cancelled because the round supposedly didn't provide amazing ballistics when utilized in a pistol.
It's the same case with the Five-Seven. It's a fine pistol, but it can't get the same performance due to the short barrel length. It still performs better than typical rounds like .45 ACP and 9mm parabellum.
There is no real thing as a PDW round, since PDWs are, by description, primarily chambered in pistol rounds. They just tend to have longer barrels, faster muzzle velocity, and a higher rate of fire than a typical pistol.
To me, personally, I think there's an advantage to having your standard PDWs to be chambered in the same rounds as your pistols, because the pistols are still better at military aspects like penetration, and on the production side it simplifies things so you're only producing 1 product as opposed to multiple.