Allowing the direct import of gltf to stage via reference or sublayer is super exciting for kitbash-
I tested a bunch of models from sketchfab. The materials work in vk/gl. the objects have a usd preview material where a material x or openpbr would be ideal. but that's not the main issue - the material looks correct in viewport. but karma shades without textures.
The step of recreating the material results in broken uvs. Simply doing an edit material on the imported material also will break uvs. this is doing nothing but running an edit material / not touching anything.
This is consistent with all sketchfab models I've tested
