My 2¢ on passkeys: until I, as someone who is comfortable reading the developer docs on the passkey spec website, can figure out how to use passkeys with my own personal tech stack — a stack that involves a phone running Graphene and Firefox, a Linux desktop and laptop running LibreWolf, and a variety of self-hosted services — passkeys are not personally useful to me.
They may be useful to other people, but I'm not in a position where I can compromise on that stack.