If you have any interest in code injection on macOS, I've made two demo repositories with write-ups:

https://github.com/iccir/ESInjectorDemo
Demonstrates Saagar Jha's method of using Endpoint Security to inject into a newly-launched process.

https://github.com/iccir/ThreadInjectorDemo
Demonstrates the "traditional" way of injecting into an already-running process via thread_create_running().