nostr:npub1yn8xzst34p57hrgpsllnv7fjvzt4vg3azu6jfjskv8cfjckh8g6qtzjfyr that's not how I understand it based on this page - https://developer.wordpress.org/block-editor/how-to-guides/themes/#types-of-themes

Seems to indicate that it needs a template, not a theme.json