It would be great if we could navigate closer to the ground, there appears to some limit about 5m above the ground
Is there a way to reduce this limit or some other way I can make navigating close to the ground work?
I wonder if adjusting the SceneView.constraints.clipDistance.near will help in your situation?
This does not change the navigation close to ground.
Using underground is a work around at present but it would be nicer to adjust the value controlling the height above terrain
If you're referring to the interactive navigation (vs setting a camera location via code) then the navigationContraint might help, but as you noted it won't prevent you from interactively navigating underground. If the goal is to create a guided experience close to the ground then a combination of these constraints will help.