Dont think that physical materials themself have an interaction/Collision channel. But they are part of my landscape through “Pyhsical Material output”. Also other actors, like bridges or road do have some physical material that need to be read.
I dont know where I should get a collision from aswell since I currently use the navmeshvolume → “recastnavmesh-default”.
For the pathing it would be great to assigne navareas that can be read by “NavigationQueryFilters”, wich can be manipulated for every actor type.