With CubeSats having evolved beyond their initial educational purpose and now being employed across a diverse range of applications, more and more private enterprises are deploying large constellations for a plethora of applications. This increased popularity and enhanced performance of the nanosatellite form factor has led to heightened demands for reliability and cost efficiency. Presently, commissioning subsystem providers has become challenging, with a prevailing trend towards seeking fully integrated platforms in the market. Paradoxically, CubeSats are now less accessible to universities and research institutions than they were a few years ago. To address these challenges, the PocketQube concept emerged. Making up the picosatellite class, and measuring 50x50x50 mm(3), they provide a cost-effective alternative, particularly for educational purposes. Students working with PocketQubes encounter design challenges akin to those faced with larger satellites. This paper comes in continuation of the IEEE-GRSS "Open PocketQube Kit" educational initiative, developed by the NanoSat-Lab at the Universitat Politecnica de Catalunya and is focused along the integration and testing of the subsystems, as well as performing a full system validation and an environmental testing. The initiative has resulted in the development of three distinct PocketQube models: PoCat-1 equipped with a VGA camera, and PoCat-2 and PoCat-3 designed for monitoring radio-frequency interference at L-band (1-2 GHz) and K-band (24-25 GHz) respectively. The latter two have undergone a series of drone campaigns in the first half of 2024, sponsored by the Frequency Allocations in Remote Sensing (FARS) Technical Committee of the IEEE Geoscience and Remote Sensing Society (GRSS).