Thank you, that it is part of OIDC provider discovery spec explains a lot.

That said, I still find it very bizzare that it's so hard to find a tangible example to see how it is in practice.

The rfc has none. Another spec including the use of it has none. In the end only completed service provider/implementers show it.

Before programmatic access happens, it needs to be written by a human. Yet the whole thing feels so human-unfriendly.

Perhaps I am biased robots.txt sets a high bar on how easy it is to find and work with?