I thought that was just default AutoFill? It allows saving passwords to your password manager too?

You can create/generate & save new login on the fly from the sign-in screen. At least with 1Password. It's clunkier than I think is strictly necessary, but it is effective.

Is that through a keyboard? Can the browser pass what I type to 1pass?

Yep, works through the keyboard. Click on the login or password field, then it gives you a key icon to get into 1Password, where you are prompted to generate a password and provide a username. Then you tell it to autofill that into the form. A little clunky but effective.

But what you cant do, (because these are all work arounds to a proper "default password manager") is have 1pass capture what you typed into a page.

Apple gives preference to Keychain and gives it special ability. Which is what MSFT got in trouble for with IE embedded into windows.

It's new functionality I think, or at least I just recently realized I can set LastPass as the default password manager on iOS.