via make.wordpress.org => original post link
Props to @scruffian for writing this dev note.
Theme Export
The “Export” feature in the Site Editor has been improved so that now you can export your whole theme, including all the edits you have made to your templates and styles. Previously the export function only gave you access to your template files. This change makes it possible to build a block theme using the site editor and easily share the zip file with anyone.