Is it possible to rebuild a Huawei (or other) phones firmware from a existing installation? I wondered, if you can install a firmware to a Huawei phone from a update.app file, could it be possible to reverse it and build the update.app back? I mean it like create a update.app from the currently installed firmware on a Huawei phone.

I need it, because i have a Huawei Y560-L01 (Firmware build Y560-L01V100R001C577B043), and it seems i cant download this update.app version anywhere. If something happens to the phone, i could repair it with the update.app. Is it possible to rebuild the update.app from the currently installed firmware on a Huawei phone?
Try a custom recovery tool. Google  Huawei Y560-L01 (Firmware build Y560-L01V100R001C577B043 toolkit. If that doesn't work, go to the official huawei website and use a flash recovery (this will erase the phone)