DuckDB is a great thing for geospatial but most important of the past decade? There's so many tools in different categories it wouldnt come near top for me. Some might be QGIS, postGIS (still the standard), ArcGIS online (still the standard), JS mapping tools like mapbox (i prefer deckgl), new data types like COG, geopackage and geoparquet, photogrammetry tools, 3d tiles, core libraries like gdal and now pdal, shapely, etc.