Apple’s iCloud for Windows includes an iCloud Password app which allows accessing and managing your keychain stored passwords on Windows. They also have a browser extension for Chrome and Edge which does autofilling in those browsers on Windows. I haven’t used them in a long time so I don’t know if they have added passkey support to them yet.
I don't sync anywhere because I don't use the Apple keychain for my passwords. No idea if there is a solution for Android but the original claim was syncing between your devices was only possible if you stayed strictly with the Apple ecosystem. This is not accurate since you can sync to Windows even if you can't sync to Android.
However the Windows sync is only possible due to Apple providing an app for use in Windows which suggests its still within the Apple ecosystem. Apple could on a whim decide to discontinue their app for Windows.
Which makes it the same as every password manager except KeepassXC which the passkey community seems to be upset to allow exporting. So commiting to the Apple solution is no different than any other. Passwords are exportable.
