An added challenge: Yubikey NFC doesn't work on iPad, only iPhone. USB operation also seems fraught. This has been so for 7+ years now. If Apple cannot get this to work with a closed ecosystem and the leading vendor, I think the technology is just not ready for mainstream.
Apple is actually doing a lot of work (largely) in the background with every OS update.
I was recently pleasantly surprised to be able to use my smartcard form factor FIDO authenticator on macOS using a CCID USB smartcard reader. Not exactly ergonomic on a laptop, but totally viable on a desktop or docking station setup with a permanently plugged in reader. Sometimes I really do miss that contactless card reader option that some Thinkpads offered...
I think they added better hardware key support at an OS level a little over two years ago. They needed all the web authn stuff for passkeys anyways, so I bet it was a necessity prerequisite.
I just got the new M4 iPad like two months ago, and my YubiKeys absolutely did not work, no matter what I tried. There are articles on apple.com and yubikey.com that explain that USB-C YubiKeys will not work with USB-C iPads because Apple's USB-C implementation isn't sending the timing info (or something like that) that the YubiKey needs to function. People were buying Lightening YubiKey and connecting them to Apple's Lightening to USB-C "camera adapter" to work around this.
I decided to double-check my YubiKeys before I responded to your post and (!!!) they work now! This is huge!
