Upgrades over Serial

My goal is to provide an upgrade to the ESP32 device i am running over serial. The device is connected to a device that has a Cell Modem but is connected to my device over RS-232.

I looked at using the rpc-service-ota and the ota-common code but I can’t find good examples of their usage directly in C.

I have two questions. Is this a good approach to solve my problem? If so can someone point me to example code of using the preferred interface in C.

Thanks.