Do they typically not? My only contact with passkeys has been the 2FA service (Duo) at my place of work, and I've got a passkey on my phone and laptop, as well as OTP push notifications, OTP SMS, or recovery code from IT. It's particularly handy with the Chromeboxes hooked into the big presentation displays since I can scan a QR code with my phone to use the passkey stashed inside it.
Slightly poor wording from me maybe. There have been cases where for example only one hardware key could be set up but other methods were available at the same time.
I remember AWS having some weird choices at some point too, not sure how they are currently.
But yeah, typically I think most services have had multiple choises available at the same time.
