I've implemented a very basic (maybe enough?) version of this in the Illuminate repository.
- Shortcodes are not supported in
block_template_part(), which we're using—maybe not for much longer—so that we can start to use the site editor for many things, but not all of them.
- It'd be nice to see the colophon rendered in the site editor in a nicer way than the shortcode block provides.
I'd be happy to submit an iteration of the Illuminate block to this repo if that makes sense. :)