I bought a New 3ds xl and added custom firmware on it. my old new 2ds broke and got the motherboard switched so i can't transfer my data. is it possible to get the save files off the new 2ds sd card and transfer the saves to my new 3ds?
NAND backup alone might not do you much good but if it was made with GodMode9 then more recent versions of that embed an essentials backup inside the NAND backup which contains your OTP IIRC which lets you decrypt the NAND backup, as well as your movable.sed which can be used to decrypt SD card content. That essentials backup should also be exported to SD as essential.exefs when you first run GodMode9.
Friend file? Do you mean LocalFriendCodeSeed_B or the file that you have to dump when hacking a 3DS with certain methods? The latter is indeed movable.sed but it's only a partial one, not sure if it's good enough to do what you want to do.