I use it all the time with Microsoft and banks....:)

Not entering my own competiition but...

Just so you folks know you can change your Microsoft Account and Office 365 account to passwordless and use these keys to login without having a password. Ideally you would have two keys (another key as a backup somewhere safe, an authenticator app such as Microsoft Authenticator which does push notifications for those accounts, or Authy and so on).

The Microsoft passwordless login is slick. You get the login prompt, touch the key and it lists all your accounts associated with that key. Click the one you want and you are logged in.

I use my Yubikey with Twitter, Facebook, Dropbox, Google, Microsoft, Yahoo and more - so many I can't even remember all of them. Plus 130 accounts on my Authy.

I use text messaging and email based two-factor authentication on my social media accounts, banking, email, gaming, and many other accounts and services.

When I last had to replace my phone I became aware of how many authenticators I had to set up.  I have 2FA by a few different authenticator apps on many online services, and some others are set up to use SMS or email as 2FA.  I wish there was more of a standard - I suppose having a single source of truth also becomes a single point of failure, but generally increasing security always seems to involve making things more difficult to consume.

My whole family generally use 2FA on all sites for which it is enabled.  Why not?

We use a combination of phone app, phone voice (callback), and other modes such as SMS text (when available).

as i have very little security any additional would be a huge plus.

I know of 2FA due to websites saying I need it but otherwise everything else is an acronym I have no idea of what it stands for. I hope FIDO is a guard dog and not one of those handbag dogs.

I use 2FA whenever possible and suggest 2FA to any organisation that does not support it.