I <3 Yubikeys - but if woot is sold out don’t forget wired magazine FREQUENTLY has a deal for one with a subscription for half this cost… Also, google will release their Titan Keys soon. https://subscribe.wired.com/subscribe/wired/115698
In short - if you know what this is for - get one and start doing 2 factor where you can. If you don’t --> https://www.wired.com/story/how-to-use-a-yubikey/
I urge you (as a netizen) consider doing Multi-Factor Authentication for all your critical stuff - EMAIL, banking, code, etc.