As does the HK, but those are also less-concealable weapons. From looking through 5e, I can't find any pistols that have silencers that are not F, which makes sense as they are generally easy to hide.
WRT to the Doberman, it's a standard accessory like the above weapons having supressors. Or cyberdecks coming with hot-sim modules as standard components (the description even laughably says illegal hot-sim mods when the rating is R) while the hot-sim module on a commlink is illegal.
It depends on the application. In my opinion (and how I would rule) silencers for pistols are illegal in all applications.