When using PBR Metallic / Roughness workflow, and trying to export the maps, Unity Presets doesn't include Glossiness (Smoothness). It should be available in export window.
There is a way to export glosiness. Under Default Channels I can manually select Glosiness from "Custom Channels" and export it using Default (project workflow) preset.
Although this way it exports the Glosiness correctly, this results in incorrect Normal format for Unity. Unity uses OpenGL type of Normal maps. But exported normal map is different type end normals become incorrect.
This is frustrating, any help or workaround is welcome. Thanks.