Is there any method to unlock bootloader? I don't care if It involves opening the phone 
Unless you already have a bootloader unlock code from at least a year ago and have it running 9.1 beta or lower, it's not possible. Huawei changed the file system to read only (EROFS) which prohibits any writing in order for the bootloader codes to work anymore with the official 9.1 update and they've successfully stopped everyone from getting new bootloader unlock codes.what about imei.by he has mentioned about bootloader unlock for Mate 20 X