navmeshobstacle: how to generate a navigation area on the cut area

hi, is there any way to create a component similar to the navigation obstacle but also assign a navigation area over the cut area?
Currently in order to do this I need to update the entire mesh with the NavMeshBuilder.UpdateNavMeshDataAsync function.
If there was some way to do the same behavior as the navigation obstacle, but also add a navigation area in the cut area, I wouldn't have to do all this and it would be very efficient.
I wish I could see the source code of the navmeshobstacle but it is not accessible.