Short post this time.

If you on Linux set up your Yubikey in smartcard mode then you can use that Yubikey without any setup at all on Windows.

Just open PuttyWincrypt, put in the host to log in to, and under Connection > SSH > Auth set Private key file for authentication to cert://*, then click Open.

It’ll ask for the PIN, you’ll have to touch the Yubikey when it’s blinking, and you’re in.