For logins, at least, they support passkeys on the desktop as well, so long as the browser does it. Which basically means Win11 or macOS, either some Blink-based browser or Safari.
redrblackr
I use my yubikey on both my android and linux (tumbleweed) with exclusively firefox, I have not found something that does not work.. Maybe you mean non-hardware passkeys built into the os? But one could just use keepassxc or like bitwarden, those work in Firefox and Linux as well