UI Patterns 2.x is at the forefront of developing SDC's. UI Patterns is a contrib module that exposes a themes SDC to the UI in different ways. For example, you can create a bootstrap row component and then use that as a Section in layout builder. Then create a Hero or Jumbotron banner component and use that as a block.

Docs:

• Drupal.org Docs
• UI Suite Docs - Authoring a component

Videos: 

• Mastering UI Patterns in Drupal 10 (Singapore, Dec-2024)
• Webwash tutorial (March 2025)
• UI Patterns 2: Unleash SDC potential, plug your components directly in Drupal UI.
• UI Suite monthly meetings
• Building a component library with SDC (Florida, Feb-2024)