The NUMEROSO activity aims to assess the benefits of integrating Signals of Opportunity (SOOPs) with GNSS signals for navigation purposes, considering both terrestrial (such as 5G mobile or WiFi) and space-based (such as those transmitted by LEO satellites, or non-terrestrial networks) SOOPs. Leveraging advanced machine learning (ML) techniques, NUMEROSO will make use of SOOPs to enhance navigation accuracy, provide a robust solution in challenging environments, and overcome traditional GNSS limitations. In diverse outdoor environments, from urban canyons to rural landscapes, NUMEROSO will demonstrate the advantages over traditional navigation methods, employing live experiments with a GNSS/SOOP receiver testbed. Finally, the ultimate goal of NUMEROSO is to design and implement an integrated GNSS/SOOP navigation testbed, suitable for mass-market receivers, overcoming challenges of size, mass, and power consumption, while providing accurate and adaptable navigation in dynamic scenarios.