Every time I look at a "how to do pure REST", it seems like doing REST correctly is building a self-describing database instead of making an API that does a thing.

Here's the thing:

Customers don't care if your application does REST correctly or not. They only care if your application works.

API consumers care about REST only as far as the HTTP API makes sense and follows well-known and well-understood conventions.

I don't think I've ever come across a self-describing API in the wild where I have to constantly self-discover URIs. (And frankly, if someone proposed something like this I'd laugh at them.) It's just needless overengineering.