NFFA-DI is the NFFA upgrade proposal for realizing a Full-Spectrum Research Infrastructure for nanoscience and nanotechnology, capable of enhancing the Italian research competitiveness on the fundamental interactions of multi-atomic matter to explore the origins of materials behaviour at all relevant dimensional and temporal scales, to describe, understand and design material solutions for engineering innovation. The rational of NFFA-DI is to integrate nanofoundry laboratories, i.e. facilities for atomically controlled growth, structural characterization of nanoobjects and nano-structured materials, including upscaling the most promising systems to the level of intermediate TRL developments, and the national facilities for the fine analysis of matter delivering synchrotron and FEL radiation (Elettra and FERMI), therefore raising the quality, reproducibility and overall competitiveness of Italian research in nanoscience, fully integrated in the European RI ESFRI landscape. NFFA-DI creates a unique environment for basic nanoscience and advanced technologies, bridging the gap between fundamental research on quantum matter and functional micro-systems for the digital transformation. The upgrade will enable frontier research projects by users and in-house, enhancing the scientific competences and productivity of all nodes, along with the continuous upgrade of the RI. Mission oriented research at EC level and NRRP Centers and Partnerships will also exploit access to NFFA-DI. The combined digital access to a wide portfolio of services through a Single Entry Point and Catalogue of state-of-the-art experimental and computational resources and FAIR-data services covers the whole value chain from material discovery to industrial technology transfer. It will become a reference RI in Europe, with huge potential for the acceleration of the digital transformation of research and society.