The problem with hardware authenticators is compatibility across devices. One job I worked at a while back used Yubikeys, which were great… if you were logging in from your work PC. If you need to access your work email from your phone, that wasn’t really an option without getting an exception made to your account, which required IT doing a manual reconfig of your account. And obviously they were reluctant to do that, because that just opened up more security risks that the Yubikeys were meant to prevent.

I mean that sounds more like a money problem to me. There all multiple different types of yubi keys that work for different types of USB and lightning as well as NFC if you want that. The only reason you wouldn’t be able to use a yubikey on your phone is because you weren’t supplied with a yubi key that works with phones and only the cheapest option with a regular USB A plug.