It turns out apparently I had two problems, one was about include the global header file, and the other was the library dependency finder configuration. By adding both lines to my platformio.ini everything compiled nicely:
build_flags = -Iinclude
lib_ldf_mode = chain+
I found this solution better than setting this configurations in a library.json file because my project is going to have several private libs, so instead of having this duplicated in every private lib, I’d rather have one global configuration.