A passkey lives on a device you control or in a password manager. If you lose your only one, you cannot elevate — which includes not being able to remove the passkey that no longer exists.
Recovery: an owner or admin contacts Ploy support, who can remove the stranded credential. You then register a fresh one, and because you hold none, that registration is not gated.
Ploy support can only ever remove a credential. Nobody at Ploy can add one to an account or verify on your behalf.