PART ONE: The "Lab on Fiber" concept envisions novel and highly functionalized technological platforms completely integrated in a single optical fiber that would allow the development of advanced devices, components and sub-systems to be incorporated in modern optical systems for communication and sensing applications. The realization of integrated optical fiber devices requires that several structures and materials at nano and micro scale are constructed, embedded and connected all together to provide the necessary physical connections and light-matter interactions. This paper reviews the strategies, the main achievements and related devices in the "Lab on Fiber" roadmap discussing perspectives and challenges that lie ahead. PART TWO: After having reviewed, in the previous part, the main results achieved in the "Lab o Fiber" roadmap through the development of several wavelength-scale devices …