Computer security is usually defined as achieving three things: Confidentiality, Integrity and Availability.
If device loss (or a google/apple account ban) leads to permanent loss of access to your (other) accounts, then passkeys aren't providing availability, so they're not secure.
Put another way: If you ignore availability, then passwords are even more secure than passkeys when used "correctly":
When creating a new account, choose a random 80 digit string for your password and don't record it anywhere. Also, don't set up an account recovery email address / phone number / etc.
