Passkeys are basically FIDO2.
FIDO2 wasn't really adopted, so now they are marketing it under a new name (while also allowing more liberal ways of storing the keys, no "normal" user would keep a FIDO2 stick with them all the time). So, you can still use your FIDO2 stick (as long as it is not too old I guess) or a password manager like KeePassXC. No need to switch to the Apple/Google/Microsoft stuff.
Gefühlt handelt jeder zweite Pfosten von GNU/Linux... mir gefällt's!