Providing modules while keeping headers
Good examples of libraries that ship modules alongside their existing headers.
bshoshany-thread-poolbshoshany/thread-pool
A good example for libraries that provide modules while keeping headers. Its README also gives a very detailed explanation of how to use the wrapped modules, which makes it a great starting point for beginners adopting modules.
Using modules natively
Projects written with modules from the ground up, to give a feeling for how developing with modules natively looks.