Hopefully better syncing comes soon but i'm ok with the current situation for now.
This is where the incentives push and is why we're unlikely to see usable or easy passkey sync.
I'm sort of ok with this (it will be a net security improvement) but it saddens me a little to see more of the web come under centralised control.
Most people won't fully understand the implications of this, which will be that the right law enforcement request will instantly unlock every service you have access to regardless of jurisdiction.
Plus lots of secondary effects relating to fed auth providers having increasing leverage over the web in general.
You are conflating the old model of "log in with Google" and the new model of Google syncing your passkeys in an E2E way. The latter is more resistant to law enforcement misuse (not 100%, see All Writs Act in the San Bernardino shooter case).
It's a nuanced discussion because in practice today, email provider is regarded as ultimate source of truth regarding identity, except for high security domains e.g. where money is involved (banks, crypto) and it's economically viable for recovery to be high touch.
So having access to a user's email is the first "golden key".
Second is OIDC / social logins.
Third would be passkeys / stored passwords / an unlocked device.
My guess about the future is that OIDC / social login will prove to scale and grow better than direct passkeys in most instances. It's a better, more fully developed model for thinking about and managing identity lifecycle, passkeys themselves are a low level primitive by comparison.
Users will understand it (social login) better, providers will support it better (partly because corporates don't have any way to centrally manage passkeys at scale, nor should they) and finally because of the fallback / recovery problem for sites using passkeys.
Backup codes, sms phone recovery, alternate recovery email are all there in all of the above.
It's no different to forgetting your password/losing access to your password manager is it? As in i've literally at points lost access with passkeys (i only had 1 at the time) and the way i got back in was very straightforward and no different to losing access to a password manager. I got an email and typed my old password and i got back in and re-setup my passkeys.
The way I assess risk, that's less likely to happen than I am to lose my passkeys.
If I'm using passkeys but can recover my account with SMS, then why am I using passkeys? That sounds like the weak link of security. I'd rather use passwords, where I can understand what the password consists of rather than passkeys if I'm not getting an increase in security.
It's unfortunately not quite the same level of portability as passwords, as I don't think there's any standardized export/import format yet, but these options are significantly better than Apples's and Google's closed ecosystems.
Eg. My Microsoft desktop, my Google phone, my Apple laptop all have passkeys setup individually that allow login to my various accounts such as my Google account.
So they aren't at all synced. They are all from different vendors but they can all login since i set them all up as passkeys. It's easy to do this too. Setup one site for passkey login via phone, go to that site on your desktop and select "auth via phone passkey" and use the phone passkey and then once logged in on the desktop go to account setup and select "Create a passkey on this device". The end result is you have multiple hardware security keys, namely your phone, desktop and laptop.