Sorry for the late reply, I haven´t had access to my 3DS until now.
It was surprisingly easy to get the agb.bin file as you suggested @B_E_P_I_S_M_A_N, I have som experience extracting 3DS VC ROMs using asia81´s "HackingToolKit3DS", so, after exporting the .cia with gm9 and unpacking it with the...