Passkeys are a vector for locking your logins to Big Tech ecosystems. They support device attestation, which means the service you are logging in to can require you to only use certain Passkey clients such as those provided by Google, Apple or Microsoft. The Passkey spec authors also maintain a list of "naughty clients"[1], which are clients that allow the user to manage their own data how they want. Services could choose to block those clients for "security reasons," justifying the decision to force you to use one of the Big Tech providers.
Until device attestation is removed or strongly curtailed in the spec, I suggest you do not create any Passkeys. Which sucks, because it's otherwise a pretty cool tech.
[1] https://passkeys.dev/docs/reference/known-issues/
More sources here: https://www.smokingonabike.com/2025/01/04/passkey-marketing-...