We plan to implement our own DFU controller on host MCU, the bootloader+softdevice+app zip file will be generated by nrftutil software.
How to exact those part firmware and send to nrf52832 module?
Is there any document to show this kind of zip file format?
If you are going to create your own DFU Contoller, you have to use the generic interface defined by the DFU protocol, which consists of a set of request commands along with opcodes. Check out the DFU BLE transport layer on how to perform DFU over BLE.
If anything is unclear or you want me to elaborate more about something, please ask.