Pitch control should work on nearly all mp3 players, including NWZ models. The question is how to get to the appropriate menu. If I understand the code correctly (see file apps/keymaps/keymap-nwz.c, line 59), on NWZ you should be able, while you're on the WPS screen, to long press the power button. This should display the context menu, with the pitch screen item.
If this does not happen then I think that some code areas are not activated in NWZ yet. I don't have the device and hence can't check.