Four lists would be needed:
All of them should have some form of “Firmware upgradeable” and “Loadable Sound Files” as needed, just to cover those items.
Multifunction decoders, Silent or Sound, because sound only is pretty rare. Just a “Sound Equipped, y/n” or something like that would suffice. Some people call the silent decoders “motor only” but that is a misnomer because they have both motor and function outputs. They can also have upgradeable firmware and user loaded sound files as well.
Function decoders, used for additional functions or animations in rolling stock
Accessory decoders, used to control accessories such as signal heads, crossing gates, and turnouts. Some are geared toward turnouts only.
A fourth option would be for sound only decoders such as SoundTraxx’s Soundcar, which is used for ambient noises such as refrigeration equipment, cattle, etc. Digitrax makes them for adding sound to a locomotive, but that is aimed more at the “budget” modeller. The current crop of MF decoders are so sophisticated that these things just don’t make much sense. They would need entries for addressing, function outputs, user loadable sounds, etc.