I do not use Cura and so I created a PrusaSlicer profile for the Elegoo Neptune 4 Pro (should also work with the non-Pro). This not perfect and there are still some things that need tweaking but it works well for me with the included PETG profile. I would suggest running a temp test print and adjusting accordingly.
The Neptune 4 runs on klipper and so there are a number of things that are baked into the firmware and thus not controlled by the slicer. This can be seen in the “Machine limits” section, I have the acceleration and feed rate turned down a lot but from what I can tell it is not something that changes the print. It seems that these values may only be used for the print time estimation (PS seems to always think it will take longer than it does).
I have some custom G-code for the start and end which purge, prime, and also turn on the lights at the begging of the print. This can be adjusted if you do not like the way it operates but proceed with caution to avoid damaging the printer!
Please let me know if there are improvements you need or other things which you find improve on this!
The author marked this model as their own original creation.