I think that you should be able to use the negative delay in Dorico. Dorico probably does support PDC (especially since it shares an audio engine with Cubase), otherwise NotePerformer probably wouldn’t have a way to read ahead and NotePerformer would be out of sync with the playhead. This is the facility that I have always believed NotePerformer to use to “read ahead” because there is no other way I know of.
I haven’t used this type of plugin in a long time. I think your issue with the DMG one is likely a user interface issue where something is confusing about how to enter things. Try the Voxengo one. I believe it treats the delay entered as a negative delay.
I also seem to recall that people on this forum previously reported using these types of plugins successfully to create negative delay in Dorico.
EDIT: What is the current method for handling negative track delay in Dorico?
Someone in that thread on vi-control reported using the Voxengo plugin to get the negative delay in Dorico last year.