FWIW, I found an explanation of api-initializers/ here:
(And that connects it to the Ember docs, and then it starts making sense.)
It still would be nice to have a basic enumeration/explanation of the directory structure possibilities in one document. (E.g., I know connectors/ is a thing… are there more?)
Also, FWIW: the Theme CLI app pulls the skeleton from:
It only mentions api-initializers/.
(I am, in fact, using the Theme CLI app, but started using it after I already had the beginnings of a theme component, so I had skipped the skeleton step.)