If any kind of mtl to abr conversion is possible, it would be something like making new Adobe Photoshop brushes (.abr) based on graphics files saved in MTL format (Wavefront material data). We have not found any specific mentions about such conversion or export, but MTL format is support in Photoshop, so technically this should be doable.
In any case, if you have issues with such export, it would be best to contact Adobe support or some Photoshop community.
Updated: January 10, 2023