Clarification on Bootloader on nRF52840

Hi,

I have working with Bootloader development on nrf52840 controller, for that i followed devacedemy course for firmware update using Uart and able to update firmware using those mcumgr commands.

In that I have one clarification like where the bootloader related code or APIs has been usen because i have checked in the project no code related to bootloader but only in the prj.conf file have some configurations on that. How the bootloader here working here like these i want to know the clarity.

Another thing is How can we check the mcumgr commands are running, how it is taking via uart.

Thank you in advance