Across its work packages, SEA2LAND delivered a coherent set of advances that moved well beyond initial expectations. WP2 mapped nutrient imbalances for N, P, Ca, K, and Mg at the NUTS3 level using national and regional datasets, while also surveying end‑user requirements and consumer acceptance, with 1,516 responses across 5countries confirming broad support for biostimulants derived from fish and aquaculture by‑products. WP3 recovered nutrients from fishery and processing residues in three pilot regions using 11 technologies, producing 13 intermediates and 14 BBFs—including three tailored mineral fertilizers (TMFs)—and surpassing its KPI with 3,437 kg of BBFs generated alongside process upscaling and mass/energy balances. WP4 treated aquaculture by‑products in 4 case studies, achieving energy‑efficient steam drying, scaling thermo‑mechanical extrusion to TRL7, recovering up to 76% P through acid extraction, and developing freshwater processing with screw press and reverse osmosis to reclaim water and nutrients. WP5 tested 26 BBFs on 10 crops across 5 countries, showing strong agronomic performance: FER3 achieved the highest N mineralization (65%) and CAT1 the best P use efficiency (45%), while modelling and ecotron trials confirmed BBFs can perform comparably to mineral fertilizers under warming and elevated CO2, with manageable environmental trade‑offs. WP6 focused on quality and safety, confirming high mineralization rates for FER3 and CAT1, identifying GHG emissions profiles, and detecting microplastics in all BBFs, while soil health studies showed enhanced microbial activity and biomass carbon despite some declines in soil fauna. WP7 assessed sustainability through LCA, LCC, and SLCA, identifying extrusion and drying as energy hotspots, and concluding that BBFs are viable when energy use is optimised, with outputs integrated into a web‑based decision support tool. WP8 developed 8 business plans and 7 case studies, analysing 62 scenarios and proving that cost‑based pricing ensures profitability, while nutrient‑based pricing leads to losses; market research across 9 EU countries highlighted regional preferences and confirmed economic viability when inputs are internalised. Finally, WP9 led communication and dissemination, exceeding targets with 45 scientific papers, 98 practice abstracts, 42 press releases, and 194 media articles, reaching over 13,000 stakeholders and engaging 261 end users, thereby ensuring uptake, replication, and alignment with EU policy objectives.