Sorry, but I don't think you do understand correctly, and I mean that in an honest and non-judgemental way, I think you may have misunderstood what Passkeys are, and what this announcement is.
With this announcement, you can log into a Google account with a Passkey. That Passkey could be generated by anything implementing the spec – an iPhone, a browser, a home-grown Python script, whatever you want.
Google can still lock you out of your Google account whether you use a Passkey or not. If you use your Google account to sign in to other sites, Google can also therefore still prevent you from logging into those other sites, as they have been able to do before (I don't know if they do this as a matter of policy, but they theoretically can).
Passkeys do not change this.
The only potential place that Passkeys might change things is if you use a Passkey generated by a Google technology, like Android or Chrome. You could use those Passkeys for logging into anything, not just Google accounts. As these are tied to a device, I don't believe the Google account on that device affects them in any way. Google can't lock you out of your Android phone, and can't prevent you using Chrome, so can't prevent you using Passkeys in either of those systems.