Best example of 2-in-1! Notion is a very innovative company. I haven’t seen any documentation site quite like this. Unfortunately, it seems to be proprietary software.
This is the best example of a “reference guide” solution that they have made to also work for “api reference” content. It’s not perfect, but conveys the information well enough.
Guides - very simple and minimal. That’s a good thing! Easy to read. Not overwhelming.
API reference - not full-featured, very bare-bones. But it’s good enough. Easy to browse.
🥇 Best use of existing guides technology to display an API reference.