This is admittedly a little farfetched, but I've come up with a way to allow renewable end stone that I think would fit well enough into the mod:

Crafting 2 end stone dust with 2 sand together could produce an end stone block, similarly to the recipe for coarse dirt.
You may also add a crushing recipe which, with Create installed, would allow obtaining 3 end stone dust (with a chance at a 4th) from an end stone block, resulting in a net positive amount of end stone dust. Voila! Renewable end stone once you've obtained a few pieces naturally (and assuming the inclusion of a mod that allows crushing recipes).

I will continue to use this locally in a data pack until I can figure out a better way to allow renewable end stone, but this is not the approach I would personally take with mod development. To be revisited once a better solution presents itself.