How can I Export Navigation Data?

Hello I am looking at the “ExportNavigationData(…)” method that is part of the FRecastNavMeshGenerator.

I was wondering what the difference is between bExportGeometry being true or false.
While I realise what it actually does I was wonder which geometry it actually exports ? Is it collision geometry ?

				const bool bExportGeometry = Element.Data.HasGeometry() && Element.ShouldUseGeometry(&DestNavMesh->NavDataConfig);

				if (bExportGeometry && Element.Data.CollisionData.Num())
					FRecastGeometryCache CachedGeometry(Element.Data.CollisionData.GetTypedData());
					IndexBuffer.Reserve( IndexBuffer.Num() + (CachedGeometry.Header.NumFaces * 3 ));
					CoordBuffer.Reserve( CoordBuffer.Num() + (CachedGeometry.Header.NumVerts * 3 ));
					for (int32 i = 0; i < CachedGeometry.Header.NumFaces * 3; i++)
						IndexBuffer.Add(CachedGeometry.Indices[i] + CoordBuffer.Num() / 3);
					for (int32 i = 0; i < CachedGeometry.Header.NumVerts * 3; i++)
					const TArray<FAreaNavModifier>& AreaMods = Element.Data.Modifiers.GetAreas();
					for (int32 i = 0; i < AreaMods.Num(); i++)
						FAreaExportData ExportInfo;
						ExportInfo.AreaId = NavData->GetAreaID(AreaMods[i].GetAreaClass());

						if (AreaMods[i].GetShapeType() == ENavigationShapeType::Convex)

							TArray<FVector> ConvexVerts;
							GrowConvexHull(NavData->AgentRadius, ExportInfo.Convex.Points, ConvexVerts);
							ExportInfo.Convex.MinZ -= NavData->CellHeight;
							ExportInfo.Convex.MaxZ += NavData->CellHeight;
							ExportInfo.Convex.Points = ConvexVerts;


the final exported obj file size is quite substantially different.

I am investigating what is the best way for me to export the Navmesh data (I need to re-use it outside of unreal) and this method seems really well suited for my needs.

Further is there any progress/update on having streamed navmesh technology ?
I am playing around with some landscape terrains and the navmesh generation only works for the terrain that sits around the world origin. If however I try to export the navmesh data just with the sub level loaded (so not going through the world composition, then the generatede navmesh is correct and i can at least export it, )