Found a version of Marlin firmware for my Neptune 2S 3D printer and installed it today. Everything went fine!
It adds various stuff, the most immediate ones for me are a much better bed levelling wizard, and the better communication with OctoPrint. Also, there is no extremely loud beep when turning on the printer, yay 😅
This is the repo for it: https://github.com/just-trey/Marlin/tree/elegoo-neptune-2/config/Elegoo/Neptune-2