That's the crux of one of the debates... members of the FIDO Consortium threatening KeePassXC and other open source tools with blocking for sharing "roaming keys", meanwhile "Oh, Apple wants to share keys via AirDrop? No problem", which is one of the concerns, that it's yet another "push users to Apple and Google's tool of choice".

There are two types of passkeys (1) resident, hardware-bound, non-copyable, installed on Yubikey etc., and (2) non-resident, copyable.

Technically, by not being copyable, a resident key isn't a "Passkey," but that's just terminology and it serves the same purpose as a passkey.