How do you approach a project if there's no library of a device available?

only written for Arduinos and most of it are at least is a combination of C and C++, so running that library on a chip that only supports C is useless.

Okay that was indeed a silly statement.

Why is there no standard of what language to use? Why would anyone use C++ in such constrained environment anyway. The world would be much simpler if everyone uses C.