I dont believe android has anything quite like sign in with apple, that lets you make an account at a service with only your name, and provides you a one time use random email address as a forwarder to your real email.

I've only seen things like parking meters and transit terminals, in which case you just pay with google pay or something. I'm not sure what the purpose of signing up for an app you don't even install is.

Presumably for services beyond parking meters and transit terminals. The keynote showed cafés, and maybe other food ordering places, too. Having an account with the establishment could be used as a loyalty rewards programme or something, like at Subway where you have a card that you scan at the till.