[justinludwig]

Yes. You can use a combination of the built-in passkey support on some of your devices (like the platform authenticators built into iOS, macOS, Windows, and Android), external hardware security keys (like YubiKey, Nitrokey, OnlyKey, etc), and/or third-party software-based authenticators (such as 1password).

Passkeys are not like passwords, where you typically register a single username+password combination for each account you use. Passkeys are more like SSH keys, where you typically register multiple SSH keys for each account you use, one for each device from which you want to access the account.

If you only use a single device or platform, it's possible to register just a single passkey for each online account you use. Even so, most technical-savvy folks will want to register at least two passkeys for each of their important accounts (to at minimum have at least one backup authenticator in case they loose access to the primary authenticator). And for accounts that you regularly access from different devices, if you find it convenient to use the built-in platform authenticator on each of those devices, you would register a separate passkey for the same account on each device.

The FAQ section of this page might help clear up some of the questions you have about passkeys:

https://fidoalliance.org/passkeys/#faq