The fundamentals for making a PWA is finally supported on iOS. Maximiliano Firtman has wrote up the basic sets of technologies now supported (and a long list of what is still missing).
So you are right, you can now install apps on iOS without App Store approval. That’s probably one reason Apple didn’t mention at all about this new ability; they might not want to confuse users. Not even the release notes on Safari mention the technologies.
Overselling the abilties of PWAs on iOS slightly — it’s not all the way there to making a real app yet!