I have looked in the WIS at the approved product list for a number of fluids and I don't think MB has any approved fluid other than their own for anything other than motor and gear oils and brake fluid.
I have looked specifically for the hydraulic fluid, the new P/S fluid, and the new trans fluid. I could just be missing it but I have found no help from MB in finding any of these fluids in anything but MB's numbers/brand.
Bosch Master, ASE Master, L1
33 years MB technician