normal maps in ObjTiles

[PerspectivesLab]

Hi there, while working with ObjTiles i figured out normal maps arent supported for the OBJ import/export
the "norm" attribute isnt featured in the official OBJ format specs, but has been extended for physically-based rendering in various softwares
read more here

Pr/map_Pr     # roughness
Pm/map_Pm     # metallic
Ps/map_Ps     # sheen
Pc            # clearcoat thickness
Pcr           # clearcoat roughness
Ke/map_Ke     # emissive
aniso         # anisotropy
anisor        # anisotropy rotation
**norm          # normal map (RGB components represent XYZ components of the surface normal)**

is that an extension that ObjTiles author would consider ? having normal map read / write feature would be usefull,
more over do you know if the 3D tiles specifications ( gltf buffer ) will allow a diffuse + normal information ?
thx