The developers have typically not given out exact drop rates for items. I know the drop rate for the wings/halo/etc. is very, very small. Plus,it’s on a timer, making it even rarer.
I doubt the overworld drops would be obtainable from the grinding device directly, based on this info from a patch note (Reborn Patch 10.90). Basically, the drops obtainable from the grinder would be anything from the loot table of mobs killed, plus the loot table for the grinder itself.
Since the overworld drops seem to be on a separate loot table, I don’t think they would be included. Though the individual mobs would still count towards the grinding device, so in that way it would still increase your chance. 