Some resources for diving into theme.json and Full Site Editing

Make WordPress Core: Introducing theme.json in WordPress 5.8

Introducing theme.json in WordPress 5.8

This post is a general introduction; it also shows how to integrate theme.json settings into blocks (useSetting).

mkaz.blog: Using theme.json in a classic theme

https://mkaz.blog/wordpress/using-themejson-in-a-classic-theme

This post describes how to add theme.json features to an existing theme, but it can also be applied to a new FSE theme. It shows very clearly the different sections of the JSON file (which is quite large and can be a little intimidating at first).

Building Modern WordPress Websites (Rich Tabor @ Wordcamp US)

Also, check his slides: Building Modern WordPress Websites

Really nice introduction to block themes, theme.json, site editor and all those kind of modern WordPress stuff.

He’s also writing some very interesting technical posts on theme.json on his blog.

Anders Norén: A New Era for WordPress Themes

A New Era for WordPress Themes

This is more of a high-profile piece on the future of WordPress Themes, by someone who must be among the best theme creators ever.

ThemeShaper on Full-site Editing

ThemeShaper is also doing a very interesting series of post on Full-site Editing, including a nice introduction to get started, templates, global styles, etc.

Finally, the Blockbase theme it’s supposed to be a good starting point for new block theme, but I’m not quite sure how it compares to the empty theme experiment (published on the WordPress official Github repo)