Statement prepartion is enabled through the connection string, and it could really help performance over time. Please see the Npgsql documentation regarding automatic preparation: https://www.npgsql.org/doc/prepare.html#automatic-preparation
To utilize spatial types with PostgreSQL you have to reference the NetTopologySuite NuGet package. Spatial types are supported on both .NET Full and .NET Standard. Spatial types are defined in the entity model in the LLBLGen Pro designer.