Standalone terrain generation

Relatively new to programming and modding in general, but I love terrain generation mods like JJThunder and Terrain Diffusion. The common problem I'm having is how long it takes for these worlds to generate. Is there a mod that turns terrain generation into its own process so I can run it when I'm not running the game? Effectively, have the terrain generation process be its own program that talks to the main server with IPC or something. I know chunky exists, but that's in game.