Overworld cliffs only worldgen

Hello, I'm trying to make a datapack that generates whole overworld as big cliffs and canyons, so that players are forced to build bridges between and live on top of them.
Has anyone made that before and could share some details? I can't get it to work.

I made a prototype, that creates high cliffs, but the cliff tops are completely flat, unfortunately. Also they're not divided into smaller ones, but instead a huge chunks of biomes. Any way to make them not-flat?