- Your Passkey Manager generally offers some form of multi-device sync. Most Passkey Managers are the same as Password Managers so it may even be a multi-device sync you are already used to.

- Devices support a flow where a QR Code kicks off a Bluetooth LE handshake between two devices to sign a one time Passkey challenge. That can be used for one time login on devices you don't sync your Password Manager to or to help bootstrap additional Passkeys on the new device.

my passkeys are in 1password, and accessible from any device i have 1password installed on. it's a very smooth experience (both adding new ones and using existing ones).

There’s support for that and has been for years. It works fine.