"Sign in with Apple" does have a very bare-bones OIDC flow in the browser on non-Apple devices/browsers. That flow takes you through a typical Apple Cloud login flow with Apple ID email and password and usual 2FA if it's the first time on that browser/device.
To meet bare minimum requirements sites like Calm.com often only show the "Sign In with Apple" button for iOS and iPadOS user agents. You can sometimes fake an iOS/iPadOS user agent and get the buttons to show up and then switch the User Agent back to get the boring in-browser OIDC flow.
As an iOS/iPadOS but Windows PC user I find it frustrating how many websites intentionally hide that button in other browsers, just when dealing with my own accounts.
I feel like Apple could maybe do a better job of education here: "please don't hide the button on non-iOS/iPadOS user agents". I hope Apple has strong developer education plans for Passkey.
To meet bare minimum requirements sites like Calm.com often only show the "Sign In with Apple" button for iOS and iPadOS user agents. You can sometimes fake an iOS/iPadOS user agent and get the buttons to show up and then switch the User Agent back to get the boring in-browser OIDC flow.
As an iOS/iPadOS but Windows PC user I find it frustrating how many websites intentionally hide that button in other browsers, just when dealing with my own accounts.
I feel like Apple could maybe do a better job of education here: "please don't hide the button on non-iOS/iPadOS user agents". I hope Apple has strong developer education plans for Passkey.