Guides for block level customization

Hi,
Currently, the customization tutorial is based on low level API, it would be nice to have a similar guides but based on block level interface, covering materials such as how to write customized blocks for different use cases, and what functions need to be implemented for the new block to work properly. It appears to be a big jump from using existing blocks to customize everything.

Personally, I'm struggling to figure out how to make new blocks work properly by looking at the source code, so I'm really looking forward to such guides.