You should be able to craft Deepslate!

I think Deepslate should be crafteble so that you can get it in Superflat Survival.
The could be a crafting recipe where you can craft deepslate with 2 cobblestone and 2 blackstone like how you can already do that to make diorite. I get that it would be a little bit op because you can build very fast automatic farms for cobblestone and blackstone(piglins), but I think that could be fixed by making it so that 2 cobblestone and 2 blackstone only combine to 1 deepslate instead of 4. Because then it wouldn't be more efficient than just getting deepslate with a tunnel bore in normal worlds, but it would make deepslate blocks accessible to Superflat Survival Players like me.