Could a "login with lemmy" replace all the login with Google/Facebook we see everywhere?
I love the convenience of not having to create a password everywhere I need to be authenticated. It would be interesting to be able to use lemmy instead of feeding more information to these big corporations.
To add to what others are saying... you really don't want or need this anyways. Once passkeys are used broadly or well supported by password managers, logins will be pretty low friction.
If you're familiar with SSH keys, it's basically the same thing but written for everything to use rather than just written for SSH.
Passkeys can also be managed by TPMs/device hardware to provide private keys that (assuming things are properly designed) can't be stolen and are bound to the device itself. This isn't a requirement however, which is why things like 1password, Chrome, etc can sync passkeys.
They're basically syncing the one-or-more private keys that back your logins.