As WordPress 5.9 draws near and brings with it Full-site Editing, setting the stage for 2022 to be filled with block-based theme releases, David Gwyer is working on a Block Theme Generator. He has released a demo video that you can view below that shows off what it’s capable of. Basically, you’ll be able to create a Theme.json file through a UI which will be the foundation of a block-based theme.
Keep in mind that it’s still at an early stage of development. Gwyer says this generator is his first web application. There’s no word yet on when it will be released to the public, but if you’d like to keep tabs on it, you can follow him on Twitter where he’s publishing updates on its progress.