[StavrosK]

> Be aware literally nothing supports this unless it's your own kernel.

Ubuntu 20.04 and later supports this, and, since that's LTS, it means that quite a few servers and machines will be supporting it already.

Github/Gitlab aren't supporting it yet, but given how great it is for security, I think they have a big incentive to speed up support.

> ed25519-ek does not work on a Yubikey <5, for example.

That's no problem, since you can just generate an ECDSA key instead, but yes, not all keys have hardware support for all algorithms.

[Freak_NL]

Debian 11 too, out of the box. It took a bit of work to use a newer openssh-client on my Ubuntu 18.04 laptop, but that was manageable.