The BM3 m2 maps just transfer over the basic M2 parameters. The M2 use totally different software BUT the same hardware. Normally BMW protect those by FSC (Preventing you from flashing the 320i into a 328i) but the M2 DME is running an incompatible eeprom so it seems they didn't bother
Replacing the eeprom in the DME is not something that can be done by bootmod or by OBD at all.