The EGR on an EU6 car is far more embedded in the whole system than they were when first introduced on EU4 cars. At that point it was just the EGR so removing/blanking wasn't so difficult.
Also the DPF on the DS is combined with the SCR for NOx, so that will be more complex, (adBlue system) and the DOC is also separate. The chances of the engine management working with all those key components missing is pretty slim. It's a pretty big reprogram of the Bosch ECU to run the engine without all that lot, and not give it all away with smoke and smell.