Cellworld is a library mod that adds data-driven biome and surface rule configurability to the nether and end dimensions in a fully compatible manner - any number of mods or datapacks can add their biomes to the default configuration through data, and they will automatically start generating. This is achieved using voronoi sampling.
Additionally, the mod adds a couple of simple biomes to the dimensions in order to demonstrate how the system works.
In order to use the mod, change the world preset to "Default Cellular" when creating a world.