Multiple Apps via IPC vs Single App with multiple .c and .h

Hello

I am finding difficult to link many apps by IPC for communicating and passing data. Originally I have multiple apps talking to each other by IPC. I am struggle to pass data like struct and references by syntax API.

Maybe I will use one big App, and many multiple .c and .h for different function.

Is there good reason to use many apps by IPC, or use one big App and many different header files?

Thanks

you can see here:

Basically the code can be reusable.
Also with IPC, you can specify particular code is sandboxed or not.