I just set up a new account and was able to register Fido2 keys without issue, but did notice that the Passkey option is not currently working (even if using the same Fido key that I was able to register as a security key).
I found I was not able to register as passkeys my Samsung Galaxy S24+, my SafeKey/Fold Fido2 key, or my SafeKey Classic Fido key. As the FIdo keys seem to work fine with the MFA method (as security keys) it would appear the issue is only related to using passkeys.