A few examples here to illustrate... The way ebay and Amazon handle this are great. Multiple passkeys allow login of multiple device ecosystems and/or hardware tokens so that users can mange their own level of risk and really any level of implementation is helps the average person.

Meta's implementation by contrast is bad, in my opinion. You are only allowed one passkey (so one login ecosystem/hardware key allowed) and it completely bypasses 2fa and security tokens. So, someone looking for more security must avoid passkeys "altogeher" and use password + U2f security key and the passkey only being allowed in a single ecosystem means that password/phishing lanes must remain open. All you're doing is disabling 2fa on a key that is likely sync'd to all of your devices. All that said...it may still be a security improvement for most users in the real world in practice, I just find it a very annoying and confusing set of security decisions.