From RealOEM, it looks like the PPF is in the secondary cats (Part ID 2)
https://www.realoem.com/bmw/enUS/sho...diagId=18_1323
UK/Europe cars have the parts with a PPF (part no's ...321 and ...322), US cars have them without (part no's ...828 and ...830).
The Akrapovic looks like a cat back exhaust and says it meets EU regulations:
https://www.akrapovic.com/en/car/pro...55&yearId=5125
Therefore, anything that looks similar should also be okay, for example the Eisenmann:
https://f90.bimmerpost.com/forums/sh....php?t=1497208