Would be great to be able to smelt stone and other blocks in forgery.

Maybe this can be done in cfg files?

Thanks.

As Alloy Forgery in concept is an enhanced Blast Furnace this is not something a recipe we are particularily considering adding at this time.
If you want to create something for yourself to be able to add recipes, this is entirely possible! This requires making a small datapack. There are many tutorials online on how to do this, and we do provide some documentation ourselves on how to do such:
https://docs.wispforest.io/datapack-tutorial/
https://docs.wispforest.io/alloy-forgery/home/