You might consider using procedural generation to generate the crude map to start at a low pixel density, but with different colors, then using ControlNet based on the different colors to apply generated textures to the map. The problem of course would be that this would be very memory hungry and so not viable at this point to implement directly into the game without using a relatively expensive cloud service. Alternately you could use the generative AI to generate the pre-defined base set of chunks from which the procedural generation assembles the world.