Is it possible to move a 3d asset from houdini to unreal engine that has a complex shader involving material mixing of triplanar textures based on attributes? Maybe with mtlx and USD? Unless there's a way to do it with principled shader/vex based shading.

No mtlx support in UE yet.

Best option would be to bake the triplanar into autouv'd textures.

If mtlx is not supported in UE is there a way to save textures on your USD file and have then transfer to unreal ?