Now I (using Safari) can use the upcoming iOS/iPadOS/macOS version’s shared password functions with my wife (who likes Chrome), all without a separate password manager.

We’ve used 1Password for ages, and I still like it a lot at work, but can probably get by with the built-in tools now.

Chrome doesn't have a TOTP authenticator, Keychain does. I don't use that feature in any password manager but some people really love it. Keychain will sync on any Windows/Mac Chromium based browser (so Edge, Brave, etc) plus Safari, so it's a little bit less locked in than Chrome but not as good as a standalone password manager.

For users with multiple Apple devices, this should enable the same password syncing and auto gen capabilities as using Safari. For me, that means a lot less hassle using Chrome as my dev browser (otherwise when I’m prompted to create a password, I switch to Safari to create/submit it, then copy from Keychain Access, which works but it’s a PITA).

It’s more geared for Apple users. I for one am really happy!!

Allows you to sign in on (iPhone) apps a bit easier I would image

No, it's just an ecosystem thing.

depends on how much you believe apple marketing. but you're right, theyre all advertising companies anyway